@article{1103039124, author = {Schaefer, H. H.}, title = {On nonlinear positive operators.}, journal = {Pacific J. Math.}, volume = {9}, number = {4}, year = {1959}, pages = { 847-860}, language = {en}, url = {http://dml.mathdoc.fr/item/1103039124} }
Schaefer, H. H. On nonlinear positive operators.. Pacific J. Math., Tome 9 (1959) no. 4, pp. 847-860. http://gdmltest.u-ga.fr/item/1103039124/