%0 Journal Article %A V. V. Basov %T Formal and analytic equivalence of real systems of differential equations %J Differencialʹnye uravneniâ %D 1977 %P 981-991 %V 13 %N 6 %I mathdoc %U http://geodesic.mathdoc.fr/item/DE_1977_13_6_a1/ %G ru %F DE_1977_13_6_a1