@article{VMUMM_1997_1_a1,
     author = {A. D. Yashin},
     title = {On the number of new logical constants in intuitionistic propositional calculus},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {7--10},
     publisher = {mathdoc},
     number = {1},
     year = {1997},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1997_1_a1/}
}