@article{DE_1983_19_10_a11,
     author = {V. K. Romanko},
     title = {Eigenvalues of boundary value problems for certain equations which change type},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1759--1764},
     publisher = {mathdoc},
     volume = {19},
     number = {10},
     year = {1983},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1983_19_10_a11/}
}