Zachary Abel, Brad Ballinger, Prosenjit Bose, Sébastien Collette, Vida Dujmovic, Ferran Hurtado, Scott Duke Kominers, Stefan Langerman, Attila Pór, David R. Wood: Every Large Point Set contains Many Collinear Points or an Empty Pentagon. Graphs Comb. 27(1): 47-60 (2011)