@article{GDZPPN002292475, title = {Homomorphism Theorems for Graphs.}, journal = {Mathematische Annalen}, volume = {154}, year = {1964}, pages = {69-80}, zbl = {0115.41005}, url = {http://dml.mathdoc.fr/item/GDZPPN002292475} }
DIRAC, G.A. Homomorphism Theorems for Graphs.. Mathematische Annalen, Tome 154 (1964) pp. 69-80. http://gdmltest.u-ga.fr/item/GDZPPN002292475/