Voir la notice de l'article provenant de la source European Digital Mathematics Library
@article{PORMA_1979__38_1-2_115366, author = {Schaefer, Paul}, title = {Mappings of positive integers and subspaces of m}, journal = {Portugaliae mathematica}, pages = {27--38}, publisher = {mathdoc}, volume = {38}, number = {1-2}, year = {1979}, mrnumber = {0682353}, zbl = {0503.47028}, language = {en}, url = {http://geodesic.mathdoc.fr/item/PORMA_1979__38_1-2_115366/} }
Schaefer, Paul. Mappings of positive integers and subspaces of m. Portugaliae mathematica, Tome 38 (1979) no. 1-2, pp. 27-38. http://geodesic.mathdoc.fr/item/PORMA_1979__38_1-2_115366/