@article{AL_1979_18_1_a3,
     author = {E. A. Palyutin},
     title = {Categorical positive {Horn} theories},
     journal = {Algebra i logika},
     pages = {47--72},
     publisher = {mathdoc},
     volume = {18},
     number = {1},
     year = {1979},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1979_18_1_a3/}
}