%0 Journal Article
%A V. G. Boltyanskii
%T The maximum principle, black holes and quasars
%J Differencialʹnye uravneniâ
%D 1979
%P 1888-1890
%V 15
%N 10
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1979_15_10_a15/
%G ru
%F DE_1979_15_10_a15