1. Anderson, A., Mayes, J.T. & Kibby, M.R.: Constructive interaction in small-group learning from hypertext. Paper presented at the Annual Conference of the British Educational Research Association. Newcastle, September 1989
2. Clark, H.H. & Marshall, C.R.: Definite reference and mutual knowledge. In: Elements of Discourse Understanding (A.K. Joshi, I.A. Sag & B.L. Webber, eds.). Cambridge: Cambridge University Press 1981
3. Crook, C.: Computers in the classroom: Defining a social context. In: Computers, Cognition and Development (J.C. Rutkowska & C. Crook, eds.). Chichester: Wiley 1987
4. Damon, W. & Phelps, E.: Critical distinctions among three approaches to peer education. International Journal of Educational Research, 13,9–19 (1989)
5. Doise, W.G. & Mugny, G.: The Social Development of the Intellect. Oxford: Pergamon 1984