Update README.md

Author: davidtheclark

README.md

@@ -57,10 +57,11 @@ These styleguides articulate conventions and guidelines for authoring scalable C
 
 > How we do CSS at [blank] ...
 
-Articles providing overviews of real-life CSS methodologies for production sites and apps of significant scale. Newest first.
+Articles providing overviews of real-life CSS methodologies for production sites and apps of significant scale. Although these articles generally don't include principles that are not better explained in the articles and longer reads above, they are so pragmatic and concrete that they are important reads in their own right. Newest first.
 
 - [Refining the Way We Structure Our CSS at Trello](http://blog.trello.com/refining-the-way-we-structure-our-css-at-trello/), by Bobby Grace (11/11/14)
 - [Medium's CSS is actually pretty f\*\*\*ing good](https://medium.com/@fat/mediums-css-is-actually-pretty-fucking-good-b8e2a6c78b06), by Jacob Thornton (8/28/14)
+- [CSS at Groupon](http://mikeaparicio.com/2014/08/10/css-at-groupon/), by Mike Aparicio (8/10/14)
 - [Codepen's CSS](http://codepen.io/chriscoyier/blog/codepens-css), by Chris Coyier (7/30/14)
 - [CSS at Lonely Planet](http://ianfeather.co.uk/css-at-lonely-planet/), by Ian Feather (7/24/14)
 - [Github's CSS](http://markdotto.com/2014/07/23/githubs-css/), by Mark Otto (7/23/14)