@article{MZM_1973_14_3_a9,
     author = {A. A. Vinogradov},
     title = {Nonaxiomatizability of directionally ordered groups in the class of nontrivially partially ordered groups},
     journal = {Matemati\v{c}eskie zametki},
     pages = {395--397},
     publisher = {mathdoc},
     volume = {14},
     number = {3},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1973_14_3_a9/}
}