@article{VMUMM_1991_6_a17,
     author = {P. G. Naumov},
     title = {Modal logics that are conservative over intuitionistic predicate calculus},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {86--90},
     publisher = {mathdoc},
     number = {6},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1991_6_a17/}
}