@article{VMUMM_1983_6_a4,
     author = {A. G. Kostyuchenko and A. A. Shkalikov},
     title = {On the theory of selfadjoint quadratic operator pencils},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {40--51},
     publisher = {mathdoc},
     number = {6},
     year = {1983},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1983_6_a4/}
}