3Hillman, D.C.A. et al. (1994). "Learner-interface interaction in distance education: an extension of contemporary, models and strategies for practitioners", American Journal of Distance Education. vol.8, no.2, 30-42.
4Holmberg, B. (1983). Theory. and Practice of Distance Education.London: Routledge.
5Laurillard. D. (2001). Rethinking university teaching: A conversational framework for the effective use of learning technologies. 2nd edn. London: Routledge.
6Moore, M. (1989). Three types of interaction, The American Journal of Distance Education, 2, 1-6.
8Mason, R.(1994). Using Communications Media for Open and Flexible Learning. London: Kogan Pages.
9Juler,P.A.(1990). Promoting interaction; maintaining independence: swallowing the mixture, Open Learning, vol.5, no.2,24-33.
10MaIsaac, M. S.and C. N. Gunawardena. (1996) Distance Education, handbook of research for educational communications and technology.Ed. D.H. Jonassen, 403-437. New York: Macmillan Library. Reference USA.
