@article{FAA_1978_12_1_a18,
     author = {V. A. Khatskevich},
     title = {An application of the contraction mapping principle in the theory of operators in an indefinite metric space},
     journal = {Funkcionalʹnyj analiz i ego prilo\v{z}eni\^a},
     pages = {88--89},
     publisher = {mathdoc},
     volume = {12},
     number = {1},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FAA_1978_12_1_a18/}
}