4Daniel,J & Marquis,C.(1979.)Interaction and Independence:Getting the Mixture Right.Teaching at A Distance 14. 被引量：1
5Ferguson,Anthony W.(1999.) Western Library Support for Distance Education:Challenges and Services.In Ding,X.(Chief Ed.) (1999d) Open and Distance Education Syatems and Models Facing 21^st Century's Information and Learning Societies.The Proceedings of 13^th Annual Conference of AAOU,October 14-17 1999.Volume 2 pp.696-711.Central Radio and TV University Beijing. 被引量：1
6Holmberg,B.(1985.)Status and trends of distance education,Second revised edition with an alphabetjcal and systematic bibliography,Lund,Lector Publishing,Sweden. 被引量：1
7Holmberg,B.(1986.)Growth and Structure of Distance Education.London:Croom Helm. 被引量：1
8Holmberg,B.(1995.)Theory and Practice of Distance Education.Second edition.London and New York:Routledge. 被引量：1
9Sewart,D.(1978.)Continuity of Concern for Students in A System of Learning at A Distance.Hagen:Fernuniversitat(ZIFF). 被引量：1
