Elsgolts, L. (1970). Differential equations and the calculus of variations. Mir.
Dyfyniad Arddull ChicagoElsgolts, L. Differential Equations and the Calculus of Variations. Moscow: Mir, 1970.
Dyfyniad MLAElsgolts, L. Differential Equations and the Calculus of Variations. Mir, 1970.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.