%0 Journal Article %A A. G. Baskakov %T Spectral analysis of differential operators with unbounded operator-valued coefficients, difference relations and semigroups of difference relations %J Izvestiya. Mathematics %D 2009 %P 215-278 %V 73 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/item/IM2_2009_73_2_a0/ %G en %F IM2_2009_73_2_a0