@article{1077490201, author = {Birkhoff, Garrett}, title = {Rings of sets}, journal = {Duke Math. J.}, volume = {3}, number = {1}, year = {1937}, pages = { 443-454}, language = {en}, url = {http://dml.mathdoc.fr/item/1077490201} }
Birkhoff, Garrett. Rings of sets. Duke Math. J., Tome 3 (1937) no. 1, pp. 443-454. http://gdmltest.u-ga.fr/item/1077490201/