Yoshimi Egawa Mariko Hagita Ken-ichi Kawarabayashi Hong Wang 0022 Covering vertices of a graph by k disjoint cycles. 114-124 2003 270 Discrete Mathematics 1-3 http://dx.doi.org/10.1016/S0012-365X(02)00831-2 db/journals/dm/dm270.html#EgawaHKW03