1. Alon, N.: The number of polytopes, configurations and real matroids. Mathematika 33(1), 62–71 (1986)
2. Aloupis, G., Ballinger, B., Collette, S., Langerman, S., Por, A., Wood, D.R.: Blocking coloured point sets. In: 26th European Workshop on Computational Geometry (EuroCG 2010), Dortmund, Germany (March 2010), arXiv:1002.0190v1 [math.CO]
3. Alpert, H., Koch, C., Laison, J.: Obstacle numbers of graphs. Discrete and Computational Geometry, 27 (December 2009), http://www.springerlink.com/content/45038g67t22463g5 (viewed on 12/26/09)
4. Arkin, E.M., Halperin, D., Kedem, K., Mitchell, J.S.B., Naor, N.: Arrangements of segments that share endpoints: single face results. Discrete Comput. Geom. 13(3-4), 257–270 (1995)
5. de Berg, M., van Kreveld, M., Overmars, M., Schwarzkopf, O.: Computational Geometry. Algorithms and Applications, 2nd edn. Springer, Berlin (2000)