@article{DE_1979_15_2_a21,
     author = {T. Sh. Kal'menov},
     title = {The spectrum of the {Tricomi} problem for a fourth-order equation of mixed type},
     journal = {Differencialʹnye uravneni\^a},
     pages = {354--356},
     publisher = {mathdoc},
     volume = {15},
     number = {2},
     year = {1979},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1979_15_2_a21/}
}