On coresets for k-means and k-median clustering.

Sariel Har-Peled Soham Mazumdar On coresets for k-means and k-median clustering. 291-300 2004 conf/stoc/2004 STOC http://doi.acm.org/10.1145/1007352.1007400 db/conf/stoc/stoc2004.html#Har-PeledM04