Harhoff, Dietmar MPI for Intellectual Property and Competition Law, Max Planck Society;
http://www.cepr.org/active/publications/discussion_papers/dp.php?dpno=9264 (Preprint)
https://doi.org/10.1111/jems.12210 (Publisher version)
Gambardella, A., Harhoff, D., & Verspagen, B. (2013). The Economic Value of Patent Portfolios. CEPR Discussion Paper, 9264.