@article{AL_2004_43_4_a0,
     author = {L. L. Maksimova},
     title = {Definability in {Normal} {Extensions} of {S4}},
     journal = {Algebra i logika},
     pages = {387--410},
     year = {2004},
     volume = {43},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_2004_43_4_a0/}
}