@article{SM_1981_38_2_a3,
     author = {I. A. Kipriyanov and L. A. Ivanov},
     title = {On lacunae for some classes of equations with singularities},
     journal = {Sbornik. Mathematics},
     pages = {217--230},
     publisher = {mathdoc},
     volume = {38},
     number = {2},
     year = {1981},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1981_38_2_a3/}
}