Voir la notice de l'article provenant de la source European Digital Mathematics Library
@article{MOMA_1965__69_177296, author = {Z. Hedrlin and A. Pultr}, title = {Symmetric {Relations} {(Undirected} {Graphs)} with {Given} {Semigroups.}}, journal = {Monatshefte f\"ur Mathematik}, pages = {318--322}, publisher = {mathdoc}, volume = {69}, year = {1965}, zbl = {0139.24803}, url = {http://geodesic.mathdoc.fr/item/MOMA_1965__69_177296/} }
Z. Hedrlin; A. Pultr. Symmetric Relations (Undirected Graphs) with Given Semigroups.. Monatshefte für Mathematik, Tome 69 (1965), pp. 318-322. http://geodesic.mathdoc.fr/item/MOMA_1965__69_177296/