Elsgolts, L. (1970). Differential equations and the calculus of variations. Mir Publishers.
Chicago Edition CitationElsgolts, L. Differential Equations and the Calculus of Variations. Moscow: Mir Publishers, 1970.
MLA Edition CitationElsgolts, L. Differential Equations and the Calculus of Variations. Mir Publishers, 1970.
Warning: These citations may not always be 100% accurate.