%0 Journal Article %A S. V. Burtsev %T Theorems on the existence of an implicit function in the theory of necessary and sufficient conditions for an extremum %J Sbornik. Mathematics %D 1995 %P 65-85 %V 82 %N 1 %U http://geodesic.mathdoc.fr/item/SM_1995_82_1_a2/ %G en %F SM_1995_82_1_a2