%0 Journal Article
%A N. L. Koval'
%T On upper and lower approximative liftings
%J Trudy Matematicheskogo Instituta imeni V.A. Steklova
%D 1985
%P 129-130
%V 40
%N 6
%I mathdoc
%U http://geodesic.mathdoc.fr/item/RM_1985_40_6_a11/
%G en
%F RM_1985_40_6_a11