@article{SM_1977_32_2_a0,
     author = {G. S. Makanin},
     title = {The problem of solvability of equations in a~free semigroup},
     journal = {Sbornik. Mathematics},
     pages = {129--198},
     year = {1977},
     volume = {32},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1977_32_2_a0/}
}