%0 Journal Article %A S. Ya. Serovaǐskiǐ %T Quasiconjugate systems and necessary conditions for optimality in nonlinear infinite-dimensional systems %J Izvestiâ vysših učebnyh zavedenij. Matematika %D 1989 %P 61-69 %N 4 %I mathdoc %U http://geodesic.mathdoc.fr/item/IVM_1989_4_a9/ %G ru %F IVM_1989_4_a9