@article{GDZPPN002300060, title = {Homomorphies\"atze f\"ur Graphen.}, journal = {Mathematische Annalen}, volume = {179}, year = {1968}, pages = {154-168}, zbl = {0165.57401}, url = {http://dml.mathdoc.fr/item/GDZPPN002300060} }
MADER, W. Homomorphiesätze für Graphen.. Mathematische Annalen, Tome 179 (1968) pp. 154-168. http://gdmltest.u-ga.fr/item/GDZPPN002300060/