@article{VMUMM_1987_3_a11,
     author = {M. A. El'-Saied},
     title = {Factorization of certain quadratic operator pencils},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {44--45},
     publisher = {mathdoc},
     number = {3},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1987_3_a11/}
}