Voir la notice de l'article provenant de la source Czech Digital Mathematics Library
@article{MASLO_1965__15_2_a3, author = {Zelinka, Bohdan}, title = {Pr\r{u}m\v{e}r grafu syst\'emu vlastn{\'\i}ch podpologrup komutativn{\'\i} pologrupy}, journal = {Mathematica slovaca}, pages = {143--145}, publisher = {mathdoc}, volume = {15}, number = {2}, year = {1965}, mrnumber = {0190041}, zbl = {0134.02504}, language = {cz}, url = {http://geodesic.mathdoc.fr/item/MASLO_1965__15_2_a3/} }
Zelinka, Bohdan. Průměr grafu systému vlastních podpologrup komutativní pologrupy. Mathematica slovaca, Tome 15 (1965) no. 2, pp. 143-145. http://geodesic.mathdoc.fr/item/MASLO_1965__15_2_a3/