@article{DAN_1979_247_4_a0,
     author = {A. P. Akimov},
     title = {On imbeddings of classical modal calculi in constructive calculi},
     journal = {Doklady Akademii Nauk},
     pages = {777--778},
     year = {1979},
     volume = {247},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1979_247_4_a0/}
}