@article{AL_1962_1_3_a1,
     author = {A. I. Kokorin and V. M. Kopytov},
     title = {Certain classes of ordered groups},
     journal = {Algebra i logika},
     pages = {21--23},
     publisher = {mathdoc},
     volume = {1},
     number = {3},
     year = {1962},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1962_1_3_a1/}
}