@article{MZM_1967_2_4_a6,
     author = {S. A. Freidkin},
     title = {The spectrum of a singular operator},
     journal = {Matemati\v{c}eskie zametki},
     pages = {379--384},
     year = {1967},
     volume = {2},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1967_2_4_a6/}
}