@article{UZKU_1969_129_4_a11,
     author = {A. V. Sul'din and V. I. Zabotin and N. P. Semenikhina},
     title = {Certain operators in {Hilbert} space},
     journal = {U\v{c}\"enye zapiski Kazanskogo universiteta. Seri\^a Fiziko-matemati\v{c}eskie nauki},
     pages = {90--95},
     publisher = {mathdoc},
     volume = {129},
     number = {4},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/UZKU_1969_129_4_a11/}
}