%0 Journal Article %A F. Z. Ziatdinov %T The spectrum of a linear second-order differential operator in a Hilbert space of vector-functions with values in an abstract Hilbert space.~I %J Izvestiâ vysših učebnyh zavedenij. Matematika %D 1964 %P 46-58 %N 6 %I mathdoc %U http://geodesic.mathdoc.fr/item/IVM_1964_6_a6/ %G ru %F IVM_1964_6_a6