@article{DAN_1983_273_1_a0,
     author = {V. S. Belonosov},
     title = {Instability indices of unbounded operators},
     journal = {Doklady Akademii Nauk},
     pages = {11--14},
     publisher = {mathdoc},
     volume = {273},
     number = {1},
     year = {1983},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1983_273_1_a0/}
}