@article{GDZPPN002288613, title = {Faktorklassen in Graphen.}, journal = {Mathematische Annalen}, volume = {141}, year = {1960}, pages = {49-67}, zbl = {0091.37603}, url = {http://dml.mathdoc.fr/item/GDZPPN002288613} }
Wagner, K. Faktorklassen in Graphen.. Mathematische Annalen, Tome 141 (1960) pp. 49-67. http://gdmltest.u-ga.fr/item/GDZPPN002288613/