@article{AL_1968_7_4_a6,
     author = {E. I. Timoshenko},
     title = {The preservation of elementary and universal equivalence in the},
     journal = {Algebra i logika},
     pages = {114--119},
     publisher = {mathdoc},
     volume = {7},
     number = {4},
     year = {1968},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1968_7_4_a6/}
}