@article{FAA_1982_16_3_a15,
     author = {N. G. Makarov},
     title = {Stability of the essential spectrum of operators close to a unitary operator},
     journal = {Funkcionalʹnyj analiz i ego prilo\v{z}eni\^a},
     pages = {72--73},
     publisher = {mathdoc},
     volume = {16},
     number = {3},
     year = {1982},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FAA_1982_16_3_a15/}
}