@article{AL_1976_15_1_a3,
     author = {A. I. Budkin},
     title = {Quasi-identities in a free group},
     journal = {Algebra i logika},
     pages = {39--52},
     publisher = {mathdoc},
     volume = {15},
     number = {1},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1976_15_1_a3/}
}