@article{IM2_1982_18_1_a4,
     author = {S. A. Nazarov},
     title = {Elliptic boundary value problems with periodic coefficients in a~cylinder},
     journal = {Izvestiya. Mathematics},
     pages = {89--98},
     year = {1982},
     volume = {18},
     number = {1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1982_18_1_a4/}
}