@article{FPM_1999_5_3_a18,
     author = {A. D. Yashin},
     title = {On a~new constant in intuitionistic propositional logic},
     journal = {Fundamentalʹna\^a i prikladna\^a matematika},
     pages = {903--926},
     publisher = {mathdoc},
     volume = {5},
     number = {3},
     year = {1999},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FPM_1999_5_3_a18/}
}