Voir la notice de l'article provenant de la source European Digital Mathematics Library
@article{PORMA_1952__11_4_114710, author = {Bergmann, Gustav}, title = {Multiplicative closures}, journal = {Portugaliae mathematica}, pages = {169--172}, publisher = {mathdoc}, volume = {11}, number = {4}, year = {1952}, mrnumber = {0052391}, zbl = {0048.02203}, language = {en}, url = {http://geodesic.mathdoc.fr/item/PORMA_1952__11_4_114710/} }
Bergmann, Gustav. Multiplicative closures. Portugaliae mathematica, Tome 11 (1952) no. 4, pp. 169-172. http://geodesic.mathdoc.fr/item/PORMA_1952__11_4_114710/