Time To Complete and Research Joint Ventures: A Differential Game Approach
In analyzing cooperation in R&D in the form of research joint ventures, the authors show that the optimal size of an RJV does not only depend on the degree of spillovers, as literature suggests, but also on the cost function of R&D activities.
Link
http://greywww.kub.nl:2080/greyfiles/center/2005/doc/29.pdf