Harhoff, Dietmar MPI for Intellectual Property and Competition Law, Max Planck Society;
Von Graevenitz, G., Wagner, S., & Harhoff, D. (2013). Incidence and Growth of Patent Thickets: The Impact of Technological Opportunities and Complexity. Journal of Industrial Economics, 61(3), 521-563. doi:10.1111/joie.12032.