A. Rahman, M. Hossain, J. Parra, и A. El Saddik. MM '09: Proceedings of the seventeen ACM international conference
on Multimedia, стр. 761--764. New York, NY, USA, ACM, (2009)
A. El Saddik, S. Fischer, и R. Steinmetz. Journal of Educational Resources in Computing, 1 (1):
Article No.~4(2001)http://www.acm.org/pubs/articles/journals/jeric/2001-1-1es/
a4-el_saddik/a4-el_saddik.pdf.