@article{AL_1990_29_6_a4,
     author = {T. G. Mustafin},
     title = {Toward a description of monoids over which all polygons have},
     journal = {Algebra i logika},
     pages = {675--695},
     year = {1990},
     volume = {29},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1990_29_6_a4/}
}