Arkadiusz Pawlik, Jakub Kozik, Tomasz Krawczyk, Michal Lason, Piotr Micek, William T. Trotter, Bartosz Walczak. Triangle-Free Geometric Intersection Graphs with Large Chromatic Number. Discrete & Computational Geometry, 50(3):714-726, 2013. [doi]
Abstract is missing.