@article{VMUMM_1990_1_a6,
     author = {E. Yu. Nogina},
     title = {Classes of arithmetic companions of modal provability logics},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {31--33},
     publisher = {mathdoc},
     number = {1},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1990_1_a6/}
}