@article{SM_1987_57_1_a1,
     author = {V. F. Veselov and S. N. Naboko},
     title = {The determinant of the characteristic function and the singular spectrum of a~nonselfadjoint operator},
     journal = {Sbornik. Mathematics},
     pages = {21--41},
     year = {1987},
     volume = {57},
     number = {1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1987_57_1_a1/}
}