W. Cushman, P. Ojha, и C. Daniels. CHI '90: Proceedings of the SIGCHI conference on Human factors
in computing systems, стр. 145--152. Association for Computing Machinery (ACM), (1990)
R. Popp, D. Montana, R. Gassner, G. Vidaver, и S. Iyer. IEEE International Conference on Systems, Man, and
Cybernetics, 3, стр. 2184--2189. San Diego, CA USA, IEEE, (11-14 October 1998)