Bernard Chazelle Herbert Edelsbrunner Michelangelo Grigni Leonidas J. Guibas Micha Sharir Emo Welzl Improved bounds on weak epsilon-nets for convex sets. 495-504 1993 conf/stoc/STOC25 STOC http://doi.acm.org/10.1145/167088.167222 db/conf/stoc/stoc1993.html#ChazelleEGGSW93