@article{MZM_1977_21_4_a2,
     author = {A. Ya. Ovsyannikov},
     title = {Lattice isomorphisms of free semigroups},
     journal = {Matemati\v{c}eskie zametki},
     pages = {459--471},
     publisher = {mathdoc},
     volume = {21},
     number = {4},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1977_21_4_a2/}
}