@article{DAN_1967_174_2_a4,
     author = {M. M. Kipnis},
     title = {A property of propositional formulas},
     journal = {Doklady Akademii Nauk},
     pages = {277--278},
     publisher = {mathdoc},
     volume = {174},
     number = {2},
     year = {1967},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1967_174_2_a4/}
}