1. Whiston, T. (and others).: Unesco-International Institute for Educational Planning, Paris, 1980. 168 pp.
2. Cabinet Office, Advisory Council.: HMSO, London, Sep. 1978. 32 pp.
3. Witt, C.R. and Galloway, E.L.: Videodisc/Videotext (USA), Winter 1982, vol 2. no. 1, pp 13–21.
4. Haefner, K.: Computers in Education: proceedings of the IFIPTC-3 3rd World Conference on Computers in Education - WCCE81, Lausanne, Switzerland, 27–31 Jul. 1981, pp 525–531.
5. North Holland, Amsterdam, 1981. 876 pp.