@article{DAN_1987_294_5_a2,
     author = {M. G. Gasymov and R. T. Pashaev},
     title = {On a fractional-linear pencil of differential operators of {Sturm{\textendash}Liouville} type},
     journal = {Doklady Akademii Nauk},
     pages = {1041--1044},
     year = {1987},
     volume = {294},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1987_294_5_a2/}
}