@article{VMUMM_1989_6_a22,
     author = {S. A. El-Sharkawy},
     title = {Distribution of the spectrum of a quadratic pencil},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {77--80},
     publisher = {mathdoc},
     number = {6},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1989_6_a22/}
}