@article{1103037131, author = {Horne, J. G.}, title = {Real commutative semigroups on the plane.}, journal = {Pacific J. Math.}, volume = {11}, number = {4}, year = {1961}, pages = { 981-997}, language = {en}, url = {http://dml.mathdoc.fr/item/1103037131} }
Horne, J. G. Real commutative semigroups on the plane.. Pacific J. Math., Tome 11 (1961) no. 4, pp. 981-997. http://gdmltest.u-ga.fr/item/1103037131/