Interesting articles on a pedagogical approach: collaborative learning

On http://tecfa.unige.ch/tecfa/publicat/dil-papers-2/Dil.7.1.14.pdf
you will find a publication of the article: What do you mean by collaborative learning? by Pieter Dillenbourg, (1999). It is free to download this article, and you don't have to be logged in on the university libary. This article is part of the book: Collaborative-learning: Cognitive and Computational Approaches. (pp.1-19).
You should read it, because it gives a very clear overview on topics concerning collaborative learning. Dillenbourg explains the variety of meanings for learning, the variety for scales, the variety of meanings for collaboration and gives attention to different theories of collaboration.

Another article, which I can recommand considering collaborative learning, is: An online collaborative environment. By Kevin Curran (2002). But you have to be logged in at the university libary. You can find this article thru ERIC. However, you can have a free preview on: http://www.springerlink.com/content/x3am1xrej06964h6/fulltext.pdf?page=1
In the article Curran (2002) describes an online collaborative learning environment that supports communication, sharing knowledge and having interaction in different ways. This article is interesting because it provides you with practical knowledge of the pedagogical approach collaborative learning.

Dillenbourg, P. (1999). What do you mean by collaborative learning? Collaborative-learning: Cognitive and Computational Approaches. Oxford: Elsevier.
Curran, K. (2002). An online collaborative environment. Education and Information Technologies, 7(1), 41–53.