@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/