Olivier Goldschmidt Dorit S. Hochbaum Cor A. J. Hurkens Gang Yu Approximation Algorithms for the <i>k</i>-Clique Covering Problem. 492-509 1996 9 SIAM J. Discrete Math. 3 http://epubs.siam.org/sam-bin/dbq/article/25232 db/journals/siamdm/siamdm9.html#GoldschmidtHHY96