@article{VMUMM_1990_3_a4,
     author = {K. Kh. Boimatov and A. G. Kostyuchenko},
     title = {Distribution of eigenvalues of second-order nonselfadjoint differential operators},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {24--31},
     publisher = {mathdoc},
     number = {3},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1990_3_a4/}
}