%0 Journal Article %A L. T. Ashchepkov %T Singular extremals of discontinuous control systems.~I %J Diskretnyj analiz i issledovanie operacij %D 1980 %P 3-13 %N 20 %I mathdoc %U http://geodesic.mathdoc.fr/item/DA_1980_20_a0/ %G ru %F DA_1980_20_a0