@article{DE_1976_12_6_a7,
     author = {M. V. Fedoryuk},
     title = {An adiabatic invariant of a system of linear oscillators, and scattering theory},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1012--1018},
     publisher = {mathdoc},
     volume = {12},
     number = {6},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1976_12_6_a7/}
}