@article{AL_1971_10_5_a5,
     author = {S. Todorinov},
     title = {Directed groups},
     journal = {Algebra i logika},
     pages = {558--560},
     publisher = {mathdoc},
     volume = {10},
     number = {5},
     year = {1971},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1971_10_5_a5/}
}