Voir la notice de l'article provenant de la source Czech Digital Mathematics Library
@article{ARM_1968__4_4_a5, author = {Zapletal, Josef}, title = {Distinguishing subsets of semi-groups and groups}, journal = {Archivum mathematicum}, pages = {241--251}, publisher = {mathdoc}, volume = {04}, number = {4}, year = {1968}, mrnumber = {0263958}, zbl = {0325.20059}, language = {en}, url = {http://geodesic.mathdoc.fr/item/ARM_1968__4_4_a5/} }
Zapletal, Josef. Distinguishing subsets of semi-groups and groups. Archivum mathematicum, Tome 04 (1968) no. 4, pp. 241-251. http://geodesic.mathdoc.fr/item/ARM_1968__4_4_a5/