Odd Crossing Number and Crossing Number Are Not the Same.

Michael J. Pelsmajer Marcus Schaefer Daniel Stefankovic Odd Crossing Number and Crossing Number Are Not the Same. 442-454 2008 39 Discrete & Computational Geometry 1-3 http://dx.doi.org/10.1007/s00454-008-9058-x db/journals/dcg/dcg39.html#PelsmajerSS08