@article{IM2_1982_19_3_a6,
     author = {O. A. Sarkisyan},
     title = {On~the word and divisibility problems in semigroups and groups without cycles},
     journal = {Izvestiya. Mathematics },
     pages = {643--656},
     publisher = {mathdoc},
     volume = {19},
     number = {3},
     year = {1982},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1982_19_3_a6/}
}