%0 Journal Article %A V. S. Mokeichev %A A. V. Mokeichev %T A~new approach to the theory of linear problems for systems of partial differential equations.~I. %J Izvestiâ vysših učebnyh zavedenij. Matematika %D 1999 %P 25-35 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/item/IVM_1999_1_a4/ %G ru %F IVM_1999_1_a4