%0 Journal Article %A V. F. Borisov %T Kelley Condition and Structure of Lagrange Manifold in a Neighborhood of a First-Order Singular Extremal %J Contemporary Mathematics. Fundamental Directions %D 2006 %P 5-44 %V 19 %U http://geodesic.mathdoc.fr/item/CMFD_2006_19_a0/ %G ru %F CMFD_2006_19_a0