@article{IVM_1971_5_a7,
     author = {L. S. Koplienko},
     title = {The spectrum of the scattering matrix},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {54--61},
     publisher = {mathdoc},
     number = {5},
     year = {1971},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1971_5_a7/}
}