@article{IM2_1968_2_3_a5,
     author = {V. B. Lidskii and V. A. Sadovnichii},
     title = {Trace formulas in the case of the {Orr{\textendash}Sommerfeld} equation},
     journal = {Izvestiya. Mathematics},
     pages = {585--600},
     year = {1968},
     volume = {2},
     number = {3},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1968_2_3_a5/}
}