extjs.com

http://extjs.com/learn/Ext_1_to_2_Migration_Guide

Wikipedia: Ext JS

http://extjs.com/deploy/dev/docs/

Anchor text: Ext JS 4.0.7 - Sencha Docs

Wikipedia: Ext JS

http://extjs.com/blog/2008/04/21/ext-js-21-and-ext-gwt-10-released-preview-of-ext-js-30/

Anchor text: Ext JS 2.1 and Ext GWT 1.0 released, preview of Ext JS 3.0 | Blog | Sencha

Wikipedia: Ext JS