Elsgolts, L., & Yankovsky, G. (1970). Differential equations and the calculus of variations. Moscow: MIR Publishers.
Παραπομπή Chicago StyleElsgolts, L., and George Yankovsky. Differential Equations and the Calculus of Variations. Moscow: MIR Publishers, 1970.
Παραπομπή MLAElsgolts, L., and George Yankovsky. Differential Equations and the Calculus of Variations. Moscow: MIR Publishers, 1970.
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