%0 Journal Article %A G. A. Seregin %T Differential properties of extremals of variational problems in the mechanics of viscoplastic media %J Informatics and Automation %D 1990 %P 117-124 %V 188 %I mathdoc %U http://geodesic.mathdoc.fr/item/TRSPY_1990_188_a5/ %G ru %F TRSPY_1990_188_a5