@article{FPM_2006_12_5_a1,
     author = {N. F. Valeev},
     title = {On localization of the spectrum of non-self-adjoint differential operators},
     journal = {Fundamentalʹna\^a i prikladna\^a matematika},
     pages = {11--19},
     publisher = {mathdoc},
     volume = {12},
     number = {5},
     year = {2006},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FPM_2006_12_5_a1/}
}