@article{DAN_1985_285_6_a1,
     author = {G. Sh. Guseinov},
     title = {On the spectral analysis of a quadratic pencil of {Sturm--Liouville} operators},
     journal = {Doklady Akademii Nauk},
     pages = {1292--1296},
     publisher = {mathdoc},
     volume = {285},
     number = {6},
     year = {1985},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1985_285_6_a1/}
}