@article{AL_1977_16_5_a1,
     author = {V. A. Gorbunov},
     title = {Coverings in lattices of quasivarieties, and independent},
     journal = {Algebra i logika},
     pages = {507--548},
     year = {1977},
     volume = {16},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1977_16_5_a1/}
}