@article{MZM_1979_25_6_a10,
     author = {D. P. Skvortsov},
     title = {Realizability and finite validity of propositional formulas with restrictions on the occurrence of implication},
     journal = {Matemati\v{c}eskie zametki},
     pages = {919--931},
     publisher = {mathdoc},
     volume = {25},
     number = {6},
     year = {1979},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1979_25_6_a10/}
}