CAL for Europe : Computer-Assisted Learning for Europe : proceedings of a conference of the European Commission on the Development of Educational Software, Enschede, The Netherlands, 25-28 May 1986 / edited by Tjeerd Plomp, Koos van Deursen, Jef Moonen. - Plomp, Tjeerd; Deursen, Koos van; Moonen, Jef (North-Holland, 1987)