← Search Econometrica Vol. 27 No. 4 1959 Calculus of Variations and Its Applications Gunter Bertram DOI10.2307/1909363 Volume27 Issue4 Pages712 Sources semanticscholar openalex crossref Cite APA 7 MLA 9 Chicago (author–date) Harvard Elsevier Harvard (JFE, JBF…) The Accounting Review Academy of Management American Marketing Association INFORMS (Management Science) Copy citation Copied ✓