@article{AL_1981_20_4_a5,
     author = {V. V. Rybakov},
     title = {Admissible rules for pretabular modal logics},
     journal = {Algebra i logika},
     pages = {440--464},
     publisher = {mathdoc},
     volume = {20},
     number = {4},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1981_20_4_a5/}
}