@article{BAG_1983__15_138249,
     author = {W. ZAHN},
     title = {Elementare {Halbordnungen}},
     journal = {Beitr\"age zur Algebra und Geometrie},
     pages = {109--120},
     publisher = {mathdoc},
     volume = {15},
     year = {1983},
     url = {http://geodesic.mathdoc.fr/item/BAG_1983__15_138249/}
}