"Four Steps to Effective Virtual Classroom Training" (2005) by Ruth Clark
http://www.clarktraining.com/content/articles/eGuildMay2005.pdf
"Harnessing the Virtual Classroom" (2005) by Ruth Clark in T+D Magazine
http://www.clarktraining.com/content/articles/HarnessingTheVC.pdf
"Tips and Techniques for More Engaging, Effective Virtual Sessions" by Sally Hovis (SkillSoft Corporation)
Live and Online! Tips, Techniques and Ready-to-use Activities for the Virtual Classroom (2004) by Jennifer Hoffmann
The New Virtual Classroom (2007) by Ruth Colvin Clark and Ann Kwinn