Voir la notice de l'article provenant de la source Math-Net.Ru
@article{MAT_1959_3_4_a1, author = {Ph. J. Higgins}, title = {Groups with multiple operators}, journal = {Matematika}, pages = {55--106}, publisher = {mathdoc}, volume = {3}, number = {4}, year = {1959}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/MAT_1959_3_4_a1/} }
Ph. J. Higgins. Groups with multiple operators. Matematika, Tome 3 (1959) no. 4, pp. 55-106. http://geodesic.mathdoc.fr/item/MAT_1959_3_4_a1/