@article{SM_1988_59_2_a7,
     author = {A. U. Muravitskii},
     title = {Algebraic proof of the separation property for an intuitionistic provability calculus},
     journal = {Sbornik. Mathematics},
     pages = {397--406},
     publisher = {mathdoc},
     volume = {59},
     number = {2},
     year = {1988},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1988_59_2_a7/}
}