@article{DE_1992_28_4_a11,
     author = {M. G. Gasymov and S. S. Mirzoyev},
     title = {Solvability of boundary value problems for second-order operator-differential equations of elliptic type},
     journal = {Differencialʹnye uravneni\^a},
     pages = {651--661},
     publisher = {mathdoc},
     volume = {28},
     number = {4},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1992_28_4_a11/}
}