Leading Trade and Textbook Publishers Provide Content in Expansion of ... - Digital Producer (press release) http://news.google.com/news/url?sa=t&fd=R&usg=AFQjCNH9wPoqORkOdQ3vDaK1peOFihMHBA&url=http://digitalproducer.digitalmedianet.com/articles/viewarticle.jsp?id%3D1221146