@article{gw-sslaago-01 , author = "B. G{\"a}rtner and E. Welzl" , title = "A simple sampling lemma - analysis and applications in geometric optimization" , journal = "Discrete Comput. Geom." , volume = "25" , number = "4" , pages = "569--590" , year = "2001 (preliminary version at SCG'2000)" }