@article{GDZPPN00228474X, title = {On Ordered Fields and Definite Functions.}, journal = {Mathematische Annalen}, volume = {129}, year = {1955}, pages = {257-271}, zbl = {0067.01502}, url = {http://dml.mathdoc.fr/item/GDZPPN00228474X} }
Robinson, A. On Ordered Fields and Definite Functions.. Mathematische Annalen, Tome 129 (1955) pp. 257-271. http://gdmltest.u-ga.fr/item/GDZPPN00228474X/