Calculus of variations / by L. E. Elsgolc. Ėlʹsgolʹt︠s︡, L. Ė. (Lev Ėrnestovich) Calculus of variations. QA315 .E513 517.4 ELC Includes index. Oxford ; New York : Pergamon Press, 1961. 1961. 1961 Text 178 p. : eng International series of monographs on pure and applied mathematics ; v. 19 International series of monographs in pure and applied mathematics ; v. 19.