@article{AL_1962_1_4_a1,
     author = {Yu. L. Ershov},
     title = {Axiomatizable classes of models with infinite signature},
     journal = {Algebra i logika},
     pages = {32--44},
     publisher = {mathdoc},
     volume = {1},
     number = {4},
     year = {1962},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1962_1_4_a1/}
}