@article{MAN_1968__178_161741,
     author = {W. MADER},
     title = {Homomorphies\"atze f\"ur {Graphen.}},
     journal = {Mathematische Annalen},
     pages = {154--168},
     publisher = {mathdoc},
     volume = {178},
     year = {1968},
     zbl = {0165.57401},
     url = {http://geodesic.mathdoc.fr/item/MAN_1968__178_161741/}
}