May 2008 Gilbane Group Inc
Digital Magazine and Newspaper Editions Growth, Trends, and Best Practices
http://www.advancedpublishing.com/resources/istudies/gilbane_report.aspx

June 2007 Online Publishers Association
Frames of Reference: Online Video Advertising, Content and Consumer Behavior
http://www.online-publishers.org/media/file/OPAFramesofReferenceFINA1024.pdf