@article{SM_1970_11_1_a8,
     author = {V. \`E. Lyantse},
     title = {Completely regular perturbation of a~continuous spectrum},
     journal = {Sbornik. Mathematics},
     pages = {115--143},
     publisher = {mathdoc},
     volume = {11},
     number = {1},
     year = {1970},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1970_11_1_a8/}
}