@article{DAN_1987_293_3_a17,
     author = {A. I. Nosich and A. E. Poedinchuk and V. P. Shestopalov},
     title = {The existence of a discrete spectrum and waves of singular type in},
     journal = {Doklady Akademii Nauk},
     pages = {587--591},
     publisher = {mathdoc},
     volume = {293},
     number = {3},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1987_293_3_a17/}
}