1. Entering the mainstream: The quality and extent of online education in the United States, 2003 and 2004;Allen,2004
2. Staying the course: Online education in the United States, 2008;Allen,2008
3. Peer interaction and problem solving: when are two heads better than one?;Azmitia;Child Development,1988
4. Characteristics of online teaching in post-secondary, formal education;Berge;Educational Technology,1997
5. Facilitating interaction in computer mediated online courses;Berge,1996