Voir la notice de l'article provenant de la source Czech Digital Mathematics Library
@article{MASLO_1973__23_3_a7, author = {Pond\v{e}l{\'\i}\v{c}ek, Bed\v{r}ich}, title = {A {Relation} for {Closure} {Operations} on a {Semigroup}}, journal = {Mathematica slovaca}, pages = {249--256}, publisher = {mathdoc}, volume = {23}, number = {3}, year = {1973}, mrnumber = {0364509}, zbl = {0265.20053}, language = {en}, url = {http://geodesic.mathdoc.fr/item/MASLO_1973__23_3_a7/} }
Pondělíček, Bedřich. A Relation for Closure Operations on a Semigroup. Mathematica slovaca, Tome 23 (1973) no. 3, pp. 249-256. http://geodesic.mathdoc.fr/item/MASLO_1973__23_3_a7/