Jansen, Jos Max Planck Institute for Research on Collective Goods, Max Planck Society;
http://dx.doi.org/10.1111/j.1530-9134.2011.00316.x (Any fulltext)
Jansen, J. (2011). On Competition and the Strategic Management of Intellectual Property in Oligopoly. Journal of Economics and Management Strategy, 20(4), 1043-1072.