@article{ZNSL_1988_169_a6,
     author = {A. R. Its and A. F. Ustinov},
     title = {Formulation of the scattering theory for the {NLS} equation with boundary conditions of the type of finite density in the soliton-free sector},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {60--67},
     publisher = {mathdoc},
     volume = {169},
     year = {1988},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1988_169_a6/}
}