Voir la notice de l'article provenant de la source Czech Digital Mathematics Library
@article{ARM_1985__21_1_a2, author = {Pilecka-Oborska, Barbara and Serafin, Stanis{\l}aw}, title = {On $x$-operators in an arbitrary semigroup}, journal = {Archivum mathematicum}, pages = {13--22}, publisher = {mathdoc}, volume = {21}, number = {1}, year = {1985}, mrnumber = {818303}, zbl = {0581.20061}, language = {en}, url = {http://geodesic.mathdoc.fr/item/ARM_1985__21_1_a2/} }
Pilecka-Oborska, Barbara; Serafin, Stanisław. On $x$-operators in an arbitrary semigroup. Archivum mathematicum, Tome 21 (1985) no. 1, pp. 13-22. http://geodesic.mathdoc.fr/item/ARM_1985__21_1_a2/