@article{IM2_1997_61_6_a1,
     author = {V. S. Guba},
     title = {On the relationship between the problems of equality and divisibility of words for semigroups with a~single defining relation},
     journal = {Izvestiya. Mathematics},
     pages = {1137--1169},
     year = {1997},
     volume = {61},
     number = {6},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1997_61_6_a1/}
}