@article{FAA_1971_5_1_a6,
     author = {L. A. Sakhnovich},
     title = {The invariance principle for generalized wave operators},
     journal = {Funkcionalʹnyj analiz i ego prilo\v{z}eni\^a},
     pages = {61--68},
     publisher = {mathdoc},
     volume = {5},
     number = {1},
     year = {1971},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FAA_1971_5_1_a6/}
}