%0 Journal Article %A Herrlich, H. %A Ringel, C. M. %T Identities in Categories %J Canadian mathematical bulletin %D 1972 %P 297-299 %V 15 %N 2 %U http://geodesic.mathdoc.fr/articles/10.4153/CMB-1972-055-0/ %R 10.4153/CMB-1972-055-0 %F 10_4153_CMB_1972_055_0