@article{1077490473, author = {Hopkins, Charles}, title = {The half-group of cosets belonging to a group}, journal = {Duke Math. J.}, volume = {4}, number = {1}, year = {1938}, pages = { 30-38}, language = {en}, url = {http://dml.mathdoc.fr/item/1077490473} }
Hopkins, Charles. The half-group of cosets belonging to a group. Duke Math. J., Tome 4 (1938) no. 1, pp. 30-38. http://gdmltest.u-ga.fr/item/1077490473/