@article{IM2_1971_5_6_a4,
     author = {Yu. I. Khmelevskii},
     title = {Systems of equations in a~free {group.~I}},
     journal = {Izvestiya. Mathematics },
     pages = {1245--1276},
     publisher = {mathdoc},
     volume = {5},
     number = {6},
     year = {1971},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1971_5_6_a4/}
}