%0 Journal Article
%A M. A. Krasnosel'skii
%A S. G. Krein
%A P. E. Sobolevskii
%T On differential equations with unbounded operators in Hilbert space
%J Doklady Akademii Nauk
%D 1957
%P 990-993
%V 112
%N 6
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1957_112_6_a2/
%G ru
%F DAN_1957_112_6_a2