@article{DAN_1973_209_2_a2,
     author = {G. A. Gurevich},
     title = {On the ranks of coefficient-free equations in a free group},
     journal = {Doklady Akademii Nauk},
     pages = {272--274},
     publisher = {mathdoc},
     volume = {209},
     number = {2},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1973_209_2_a2/}
}