@article{CM_1951__9__130_0, author = {Loonstra, F.}, title = {The classes of partially ordered groups}, journal = {Compositio Mathematica}, volume = {9}, year = {1951}, pages = {130-140}, mrnumber = {45740}, zbl = {0043.25602}, language = {en}, url = {http://dml.mathdoc.fr/item/CM_1951__9__130_0} }
Loonstra, F. The classes of partially ordered groups. Compositio Mathematica, Tome 9 (1951) pp. 130-140. http://gdmltest.u-ga.fr/item/CM_1951__9__130_0/