1U.S. Department of Education. Evaluation of Evi- dence-Based Practices in Online Leaming:A Meta-Anal- ysis and Review of Online Learning Studies[DB/OL]. http://www.sri.com/sites/default/files/publications/im- ports/Evaluation Evidence Based Practice Online Learning. pdf,2015-01-18.
2Allen, I. & Seamand.. Sizing the Opportunity:The Quality and Extent of Online Education in the UnitedStates,2002 and 2003 [DB/OL]. http://files.eric.ed.gov/fiall- text/ED530060.pdf, 2014-12-26.
3Scardamalia,M. & Bereiter,C.. Computer Support for Knowledge-Building Communities [J]. The Journal of the Learning Sciences,1994,3(3):265-283.
4Ueris,K.. The Three Dimensions of Learning[M]. Malabar, Florida : Krieger Publishing Company, 2004. 20- 121.