The announcement by the Tamil Nadu government allowing post-production work on films and television projects to resume from May 11 was welcomed by the

A person from Kuchipalayam tested positive for COVID-19 even as Mahe became COVID-free with the sole patient testing negative for the infection and ge

CM takes decision following representations from industry

Chennai adds 399 patients to its total

The Madras High Court on Friday directed the State government to close all 3,850 liquor shops run by the Tamil Nadu State Marketing Corporation (Tasma

The Madras High Court on Friday warned the State government of being imposed with costs if it fails to file a counter affidavit by Tuesday to a public

The Tamil Nadu Consumer Protection Organisation has asked the Tamil Nadu government to form a committee of officials from the environment, industries

The second Shramik special train with 1,131 passengers left Kadpadi junction for Ranchi on Friday at 7.40 p.m. The passengers were brought to the stat

Molly Wilson and Eileen Wagner battle the age old Christmas issues of right and wrong, good and evil, and how the messages we send through iconography design can impact the decisions users make around important issues of security. Are you icons wise men, or are they actually King Herod?

Congratulations, you’re locked out! The paradox of security visuals

Designers of technology are fortunate to have an established visual language at our fingertips. We try to use colors and symbols in a way that is consistent with people’s existing expectations. When a non-designer asks a designer to “make it intuitive,” what they’re really asking is, “please use elements people already know, even if the concept is new.”

Lots of options for security icons

We’re starting to see more consistency in the symbols that tech uses for privacy and security features, many of them built into robust, standardized icon sets and UI kits. To name a few: we collaborated with Adobe in 2018 to create the Vault UI Kit, which includes UI elements for security, like touch ID login and sending a secure copy of a file. Adobe has also released a UI kit for cookie banners.

Even UI kits that aren’t specialized in security and privacy include icons that can be used to communicate security concepts, like InVision’s Smart Home UI Kit. And, of course, nearly every icon set has security-related symbols, from Material Design to Iconic.

Many of these icons allude to physical analogies for the states and actions we’re trying to communicate. Locks and keys; shields for protection; warning signs and stop signs; happy faces and sad faces. Using these analogies helps build a bridge from the familiar, concrete world of door locks and keyrings to the unfamiliar, abstract realm of public- and private-key encryption.

When concepts don’t match up

Many of the concepts we’re working with are pairs of opposites. Locked or unlocked. Private or public. Trusted or untrusted. Blocked or allowed. Encouraged or discouraged. Good or evil. When those concept pairs appear simultaneously, however, we quickly run into UX problems.

Take the following example. Security is good, right? When something is locked, that means you’re being responsible and careful, and nobody else can access it. It’s protected. That’s cause for celebration. Being locked and protected is a good state.

Whoops.

If the user didn’t mean to lock something, or if the locked state is going to cause them any inconvenience, then extra security is definitely not good news.

Another case in point: Trust is good, right? Something trusted is welcome in people’s lives. It’s allowed to enter, not blocked, and it’s there because people wanted it there. So trusting and allowing something is good.

Nope. Doesn’t work at all. What if we try the opposite colors and iconography?

That’s even worse. Even though we, the designers, were trying both times to keep the user from downloading malware, the user’s actual behavior makes our design completely nonsensical.

Researchers from Google and UC Berkeley identified this problem in a 2016 USENIX paper analyzing connection security indicators. They pointed out that, when somebody clicks through a warning to an “insecure” website, the browser will show a “neutral or positive indicator” in the URL bar – leading them to think that the website is now safe. Unlike our example above, this may not look like nonsense from the user point of view, but from a security standpoint, suddenly showing “safe/good” without any actual change in safety is a pretty dangerous move.

The deeper issue

Now, one could file these phenomena under “mismatching iconography,” but we think there is a deeper issue here that concerns security UI in particular. Security interface design pretty much always has at least a whiff of “right vs. wrong.” How did this moralizing creep into an ostensibly technical realm?

Well, we usually have a pretty good idea what we’d like people to do with regards to security. Generally speaking, we’d like them to be more cautious than they are (at least, so long as we’re not trying to sneak around behind their backs with confusing consent forms and extracurricular data use). Our well-intentioned educational enthusiasm leads us to use little design nudges that foster better security practices, and that makes us reach into the realm of social and psychological signals. But these nudges can easily backfire and turn into total nonsense.

Another example: NoScript

“No UX designer would be dense enough to make these mistakes,” you might be thinking.

Well, we recently did a redesign of the open-source content-blocking browser extension NoScript, and we can tell you from experience: finding the right visual language for pairs of opposites was a struggle.

NoScript is a browser extension that helps you block potential malware from the websites you’re visiting. It needs to communicate a lot of states and actions to users. A single script can be blocked or allowed. A source of scripts can be trusted or untrusted. NoScript is a tool for the truly paranoid, so in general, wants to encourage blocking and not trusting. But:

“An icon with a crossed-out item is usually BAD, and a sign without anything is usually GOOD. But of course, here blocking something is actually GOOD, while blocking nothing is actually BAD. So whichever indicators NoScript chooses, they should either aim to indicate system state [allow/block] or recommendation [good/bad], but not both. And in any case, NoScript should probably stay away from standard colors and icons.”

So we ended up using hardly any of the many common security icons available. No shields, no alert! signs, no locked locks, no unlocked locks. And we completely avoided the red/green palette to keep from taking on unintended meaning.

Navigating the paradox

Security recommendations appear in most digital services are built nowadays. As we move into 2020, we expect to see a lot more conscious choice around colors, icons, and words related to security. For a start, Firefox already made a step in the right direction by streamlining indicators for SSL encryption as well as content blocking. (Spoilers: they avoided adding multiple dimensions of indicators, too!)

The most important thing to keep in mind, as you’re choosing language around security and privacy features, is: don’t conflate social and technical concepts. Trusting your partner is good. Trusting a website? Well, could be good, could be bad. Locking your bike? Good idea. Locking a file? That depends.

Think about the technical facts you’re trying to communicate. Then, and only then, consider if there’s also a behavioral nudge you want to send, and if you are, try to poke holes in your reasoning. Is there ever a case where your nudge could be dangerous? Colors, icons, and words give you a lot of control over how exactly people experience security and privacy features. Using them in a clear and consistent way will help people understand their choices and make more conscious decisions around security.

About the author

Molly Wilson is a designer by training and a teacher at heart: her passion is leveraging human-centered design to help make technology clear and understandable. She has been designing and leading programs in design thinking and innovation processes since 2010, first at the Stanford d.school in Palo Alto, CA and later at the Hasso-Plattner-Institut School of Design Thinking in Potsdam, Germany. Her work as an interaction designer has focused on complex products in finance, health, and education. Outside of work, talk to her about cross-cultural communication, feminism, DIY projects, and visual note-taking.

Molly holds a master’s degree in Learning, Design, and Technology from Stanford University, and a bachelor’s degree magna cum laude in History of Science from Harvard University. See more about her work and projects at http://molly.is.

Eileen Wagner is Simply Secure’s in-house logician. She advises teams and organizations on UX design, supports research and user testing, and produces open resources for the community. Her focus is on information architecture, content strategy, and interaction design. Sometimes she puts on her admin hat and makes sure her team has the required infrastructure to excel.

She previously campaigned for open data and civic tech at the Open Knowledge Foundation Germany. There she helped establish the first public funding program for open source projects in Germany, the Prototype Fund. Her background is in analytic philosophy (BA Cambridge) and mathematical logic (MSc Amsterdam), and she won’t stop talking about barbershop music.

More articles by Molly Wilson & Eileen

Stuart Robson rolls up his sleeves and begins to piece together the jigsaw puzzle that is design tokens and component based design. Starting with the corners, and working around the edges, Stu helps us to piece together a full picture of a modern design system.

If you stare at your twitter feed long enough, it can look like everyone is talking about Design Systems. In some cases you could be persuaded to think how shallow the term can go.

“Isn’t this what we called Style Guides?”, “Here’s my React Design System”, “I’ve just updated the Design System in Sketch”

To me, they are some and all of these things. Over the last 4 years of consulting with two clients on their Design System, my own view has changed a little.

If you dig a little deeper into Design Systems twitter you will probably see the term “Design Tokens” pop up at least once a day somewhere. Design Tokens came out of work that was being done at Salesforce with Jina and others who pioneered the creation of Design Tokens as we know them today – creating the first command line tool in Theo that had started the adoption of Design Tokens to the wider Design Systems Community.

A cool term but, what are they?

If you look at your client work, your companies site, the project you’re working on you should notice some parts of the page have a degree of consistency: the background colour of your form buttons is the same colour as your link text, or your text has the same margin, or your card elements have the same spacing as your media object.

These are design decisions, and they should be littered across the overall design of your project. These decisions might start off in a Sketch file and make their way into code from detailed investigation of a Sketch file, or you may find that the design evolves from your design application once it gets into code.

These design decisions can change, and to keep them synchronised across design and development in applications, as well as a larger documentation site in your Design System, is going to take some effort.

This is where Design Tokens come in, and I find the best way to succinctly reiterate what they are is via the two following quotes…

“Design Tokens are an abstraction for everything impacting the visual design of an app/platform.”
– Sönke Rohde

…and

“We use them in place of hard-coded values in order to maintain a scale-able and consistent visual system.”
– Jina

There are several global design decisions that we can abstract to create a top level design token – Sizing, Font Families, Font Styles, Font Weights, Font Sizes, Line Heights, Border Styles, Border Colours, Border Radius, Horizontal Rule Colours, Background Colours, Gradients, Background Gradients, Box Shadows, Filters, Text Colours, Text Shadow, Time, Media Queries, Z Index, Icons – these can all be abstracted as required.

So, spicy Sass variables?

We can look at Design Tokens as an abstraction of CSS, sort of like Sass variables, but spicier. Looking at them like this we can see that they are (in either .yaml or .json) a group of related key value pairs with more information that can be added as needed.

The great thing with abstracting design decisions outside of your CSS pre-processor is that you’re not tying those decisions to one platform or codebase.

As a crude example, we can see here that we are defining a name and a value that could then become our color, background-color, or border-color, and more.

# Colours
# -------
- name: color-red
  value: #FF0000
- name: color-green
  value: #00FF00
- name: color-blue
  value: #0000FF
- name: color-white
  value: #FFFFFF
- name: color-black
  value: #000000

These can then generate our Sass variables (as an example) for our projects.

$color-red: #FF0000 !default;
$color-green: #00FF00 !default;
$color-blue: #0000FF !default;
$color-white: #FFFFFF !default;
$color-black: #000000 !default;

Why are they so good

Ok, so we now know what Design Tokens are, but why do we need them? What makes them better than our existing solutions (css pre-processors) for defining these design decisions?

I think there are 5 really good reasons why we all should start abstracting these design decisions away from the CSS that they may live in. Some of these reasons are similar to reasons some developers use a pre-processor like Sass, but with added bonuses.

Consistency

Much like using a CSS pre-processor or using CSS custom properties, being able to define a background colour, breakpoint, or font-size in more than one place using the same key ensures that we are using the Sass values across the entire product suite we are developing for.

Using our Design Tokens in their generated formats, we can be sure to not end up with 261 shades of blue.

Maintainability

By using a pre-processor like Sass, or using native CSS custom properties, we can already have maintainable code in our projects. Design Tokens also do this at the abstracted level as well.

Scalability

“Design Tokens enable us to scale our Design across all the permutations.”
– Jina

At this point, we’re only talking about abstracting the design decisions for use in CSS. Having Design Tokens allows design to scale for multiple brands or multiple projects as needed.

The main benefit of Design Tokens in regards to scalability is the option that it gives us to offer the Design Tokens for other platforms and frameworks as needed. With some of the tools available, we can even have these Tokens shared between applications used by designers and developers.

Your marketing site and your iOS application can soon share the same design decisions codified, and you can move towards creating an Android app or web application as required.

Documentation

If we abstract the design decisions from one platform specific programming language it would be no good if it wasn’t made to be easily accessible.

The tools and applications available that are mentioned later in this article can now create their own documentation, or allow you to create your own. This documentation is either hosted within a web-based application or can be self-hosted with the rest of your Design Systems documentation.

Most of the command line tools go further and allow you do add more details that you wish to convey in the documentation, making it as unique as it is required for your project.

Empowerment

When you abstract your design decisions to Design Tokens, you can help empower other people on the project. With the tools available today, and the tools that are just around the corner, we can have these design decisions determined by anyone on the team.

No-one necessarily needs to understand how to set up the codebase to update the colour slightly. Some of the tools I mention later on allow you to update the Design Tokens in the browser.

Design Systems are already “bridging the gap” between design and development. With Design Tokens and the tooling available, we can create better team relationships by closing that gap instead.

Some of the benefits of creating and using Design Tokens are the same as using a pre-processor when it comes to authoring CSS. I feel the added bonuses of being able to empower other team members and document how you use them, as well as the fundamental reasoning in that they can be platform agnostic, are all great “selling points” to why you need to start using Design Tokens today.

Tools

There are several tools available to help you and your team to create the required files from your abstracted Design Tokens:

Command Line Tools

There are several tools available on the command line that can be used as part of, or separate to, your development process.

These tools allow you to define the Design Tokens in a .json or .yaml file format which can then be compiled into the formats you require.

Some have built in functions to turn the inputted values to something different when compiled – for example, turning hexadecimal code that is a Design Token into a RGB value in your .css file. These command line tools, written in JavaScript, allow you to create your own ways in which you want things transformed.

My current client has certain design decisions for typography in long form content (font size, weight, line height and margins) which need to be together to make sense. Being able to write JavaScript to compile these design decisions into an independent Sass map for each element allows us to develop with assurance that the long form content has the correct styling.

WYSIWYG Tools

WYSIWYG (What You See Is What You Get Tools) have been around for almost as long as we have been able to make websites. I can just about remember using Dreamweaver 2, before I knew what a <table> was.

When browsers started to employ vendor prefixes to new CSS for their browsers, a flurry of online WYSIWYG tools came with it built in. They’re still there, but the industry has moved on.

Design Tokens also have a few WYSIWYG tools available. From simpler online tools that allow you to generate the correct Sass variables needed for your design decisions to tools that store your decisions online and allow you to export them as npm packages.

These types of tools for creating Design Tokens can help empower the team as a whole, with some automatically creating documentation which can easily be shared with a url.

Retrofitting Tools

If you are starting from scratch on a new re-design or on a new project that requires a Design System and Tokens, the many of the tools mentioned above will help you along your way. But what if you’re in the middle of a project, or you have to maintain something and want to start to create the parts required for a Design System?

Luckily there are several tools and techniques to help you make a start.

One new tool that might be useful is Superposition. Currently in private beta with the public release set for Q1 of 2020 Superposition helps you “Extract design tokens from websites and use them in code and in your design tool.”

Entering your domain gives you a nice visual documentation of your sites styles as Design Tokens. These can then be exported as Sass Variables, CSS Custom Properties, JavaScript with the team working on exports to iOS and Android.

If you have an existing site, this could be a good first step before moving to one of the other tools mentioned above.

You could also make use of CSSStats or Project Wallace’s Analysis page that I mentioned earlier. This would give you an indication of what Design Tokens you would need to implement.

Component Based Design

So, we’ve created our Design Tokens by abstracting the design decisions of brand colours, typography, spacing and more. Is that as far as we can go?

Levels of Design Decisions

Once we have created our first set of Design Tokens for our project, we can take it that little bit deeper. With command line tools and some of the applications available, you can link these more global decisions to a more deeper level.

For example, you can take your chosen colours and make further design decisions on the themes of your project, such as what the primary, secondary, or tertiary colours are or what your general component and layout spacing will be.

With this, we can go one step further. We could also define some component specific design decisions that can then be compiled for the developer to use. Invest in time to check over the designs with a fine toothcomb and make sure you are using the correct Sass variable or CSS custom property for that component.

If you are going more than one or two levels of design decision making, you can compile each set of these Design Tokens to your Sass variables which can then be used as required. So you can provide: global, theme, component level Sass variables which can be used in the project. Or you could choose to only compile what you need for the components you are creating.

Variables, Maps, Custom Properties

Some of the tools available for creating and maintaining your Design Tokens allow you to compile to certain programming languages.

With my current client work, I am making use of Sass variables, Sass maps, and CSS custom properties. The Design Tokens are compiled into one or more of these options depending on how they will be used.

Colours are compiled as global Sass variables, inside of a couple of Sass maps and CSS custom properties. Our macro layout breakpoints are defined as a single Sass map.

If we know we are creating a component that has the ability to be themed, we can make use of CSS custom properties to reduce the amount of CSS we need to override, and also allow us to inline things that can be changed via a CMS as required. Which leaves us using Sass variables for parts of a component that won’t change. We are using Sass maps differently still. As mentioned, we generate a Sass map containing the design decisions for each element of text, and we can use long form text. This Sass map is then compiled into separate CSS declarations as needed using Sass mixins.

I find the beauty of being able to make use of the global, themed, and component level design decisions by compiling them into various formats (that essentially become CSS) and that gives us more power in authoring components.

Creating Consistent Utility Classes

As you have created your more global generic design decisions, you can create your own small set of utility classes.

Using a pre-processor like Sass you can define a set of mixins and functions that can take your Design Tokens that have been compiled down into variables and maps and generate separate classes for each design decision.

By making tokens available to all digital teams, we can enable them to create custom experiences that are aligned to current visual standards when a component does not (or will not) exist in the design system. Maya King

In creating utility classes with Design Tokens (using something like Sass) you have consistency with the overall Design System for times when you or a team need to create a one-off component for a project.

These exceptions tend to be something that won’t make it as part of the overall Design System, but it still needs that look and feel.

Having classes available that we can guarantee use the generic, global design decisions from the Design Tokens means these one-off components should be well on their way to have the overall look and feel of the project, and will get any updates with little to no additional overhead.

Wrapping Up

I think we are starting to see the potential of using Design Tokens as Design Systems become even more popular. I think that, from this overview, we can see how they can help us close the gap that still exists in places between the designers and developers on the team. They can help empower people who do not code to make changes that can be automatically updating live work.

I think you can start now. You may not have or need what you could term “a fully-fledged Design System” but this small step will help move towards one in the future and give you instant benefits of consistency and maintainability now. If you want more Design Tokens, as well as the links that are dotted around this article I also maintain a GitHub repo of Awesome Design Tokens which I try to keep updated with links to tools, articles, examples, videos, and anything else that’s related to Design Tokens.

About the author

Stuart Robson is a freelance front-end developer and design systems advocate who curates the design systems newsletter - news.design.systems

More articles by Stuart

Chris Mills brushes up his shorthand and shows how the MediaStream Recording API in modern browsers can be used to capture audio directly from the user’s device. Inching ever closer to the capabilities of native software, it truly is an exciting time to be a web developer.

The MediaStream Recording API makes it easy to record audio and/or video streams. When used with MediaDevices.getUserMedia(), it provides an easy way to record media from the user’s input devices and instantly use the result in web apps. This article shows how to use these technologies to create a fun dictaphone app.

A sample application: Web Dictaphone

To demonstrate basic usage of the MediaRecorder API, we have built a web-based dictaphone. It allows you to record snippets of audio and then play them back. It even gives you a visualisation of your device’s sound input, using the Web Audio API. We’ll just concentrate on the recording and playback functionality in this article, for brevity’s sake.

You can see this demo running live, or grab the source code on GitHub. This has pretty good support on modern desktop browsers, but pretty patchy support on mobile browsers currently.

Basic app setup

To grab the media stream we want to capture, we use getUserMedia(). We then use the MediaRecorder API to record the stream, and output each recorded snippet into the source of a generated <audio> element so it can be played back.

We’ll first declare some variables for the record and stop buttons, and the <article> that will contain the generated audio players:

const record = document.querySelector('.record');
const stop = document.querySelector('.stop');
const soundClips = document.querySelector('.sound-clips');

Next, we set up the basic getUserMedia structure:

if (navigator.mediaDevices && navigator.mediaDevices.getUserMedia) {
   console.log('getUserMedia supported.');
   navigator.mediaDevices.getUserMedia (
      // constraints - only audio needed for this app
      {
         audio: true
      })

      // Success callback
      .then(function(stream) {

      })

      // Error callback
      .catch(function(err) {
         console.log('The following `getUserMedia` error occured: ' + err);
      }
   );
} else {
   console.log('getUserMedia not supported on your browser!');
}

The whole thing is wrapped in a test that checks whether getUserMedia is supported before running anything else. Next, we call getUserMedia() and inside it define:

• The constraints: Only audio is to be captured for our dictaphone.
• The success callback: This code is run once the getUserMedia call has been completed successfully.
• The error/failure callback: The code is run if the getUserMedia call fails for whatever reason.

Note: All of the code below is found inside the getUserMedia success callback in the finished version.

Capturing the media stream

Once getUserMedia has created a media stream successfully, you create a new Media Recorder instance with the MediaRecorder() constructor and pass it the stream directly. This is your entry point into using the MediaRecorder API — the stream is now ready to be captured into a <Blob>, in the default encoding format of your browser.

const mediaRecorder = new MediaRecorder(stream);

There are a series of methods available in the MediaRecorder interface that allow you to control recording of the media stream; in Web Dictaphone we just make use of two, and listen to some events. First of all, MediaRecorder.start() is used to start recording the stream once the record button is pressed:

record.onclick = function() {
  mediaRecorder.start();
  console.log(mediaRecorder.state);
  console.log("recorder started");
  record.style.background = "red";
  record.style.color = "black";
}

When the MediaRecorder is recording, the MediaRecorder.state property will return a value of “recording”.

As recording progresses, we need to collect the audio data. We register an event handler to do this using mediaRecorder.ondataavailable:

let chunks = [];

mediaRecorder.ondataavailable = function(e) {
  chunks.push(e.data);
}

Last, we use the MediaRecorder.stop() method to stop the recording when the stop button is pressed, and finalize the Blob ready for use somewhere else in our application.

stop.onclick = function() {
  mediaRecorder.stop();
  console.log(mediaRecorder.state);
  console.log("recorder stopped");
  record.style.background = "";
  record.style.color = "";
}

Note that the recording may also stop naturally if the media stream ends (e.g. if you were grabbing a song track and the track ended, or the user stopped sharing their microphone).

Grabbing and using the blob

When recording has stopped, the state property returns a value of “inactive”, and a stop event is fired. We register an event handler for this using mediaRecorder.onstop, and construct our blob there from all the chunks we have received:

mediaRecorder.onstop = function(e) {
  console.log("recorder stopped");

  const clipName = prompt('Enter a name for your sound clip');

  const clipContainer = document.createElement('article');
  const clipLabel = document.createElement('p');
  const audio = document.createElement('audio');
  const deleteButton = document.createElement('button');

  clipContainer.classList.add('clip');
  audio.setAttribute('controls', '');
  deleteButton.innerHTML = "Delete";
  clipLabel.innerHTML = clipName;

  clipContainer.appendChild(audio);
  clipContainer.appendChild(clipLabel);
  clipContainer.appendChild(deleteButton);
  soundClips.appendChild(clipContainer);

  const blob = new Blob(chunks, { 'type' : 'audio/ogg; codecs=opus' });
  chunks = [];
  const audioURL = window.URL.createObjectURL(blob);
  audio.src = audioURL;

  deleteButton.onclick = function(e) {
    let evtTgt = e.target;
    evtTgt.parentNode.parentNode.removeChild(evtTgt.parentNode);
  }
}

Let’s go through the above code and look at what’s happening.

First, we display a prompt asking the user to name their clip.

Next, we create an HTML structure like the following, inserting it into our clip container, which is an <article> element.

<article class="clip">
  <audio controls></audio>
  <p>_your clip name_</p>
  <button>Delete</button>
</article>

After that, we create a combined Blob out of the recorded audio chunks, and create an object URL pointing to it, using window.URL.createObjectURL(blob). We then set the value of the <audio> element’s src attribute to the object URL, so that when the play button is pressed on the audio player, it will play the Blob.

Finally, we set an onclick handler on the delete button to be a function that deletes the whole clip HTML structure.

So that’s basically it — we have a rough and ready dictaphone. Have fun recording those Christmas jingles! As a reminder, you can find the source code, and see it running live, on the MDN GitHub.

This article is based on Using the MediaStream Recording API by Mozilla Contributors, and is licensed under CC-BY-SA 2.5.

About the author

Chris Mills manages the MDN web docs writers’ team at Mozilla, which involves spreadsheets, meetings, writing docs and demos about open web technologies, and occasional tech talks at conferences and universities. He used to work for Opera and W3C, and enjoys playing heavy metal drums and drinking good beer.

More articles by Chris

Thousand Oaks : SAGE Publishing, 2019

Cambridge, Mass. : National Bureau of Economic Research, 2020

Cambridge, Mass. : National Bureau of Economic Research, 2020

New York : Springer, [2007]

Cambridge, Mass. : National Bureau of Economic Research, 2020

Dewey Library - HX236.5.S6293 2020

Dewey Library - HV9506.R53 2019

Online Resource

Dewey Library - JK2356.G76 2019

Dewey Library - HV6638.5.M4 M55 2019

Dewey Library - JK2071.H57 2019

Dewey Library - JC573.2.U6 W54 2019

Dewey Library - JC573.2.U6 D8354 2020

Online Resource

Online Resource

Dewey Library - JC491.K255 2020

Dewey Library - JC251.A74 A83 2019

Online Resource