著者名,書名,版表示,出版者名,出版年,シリーズ名,番号,ISBN,ISSN,URL "Ėlʹsgolʹt︠s︡, L. Ė. (Lev Ėrnestovich)",Calculus of variations,,Addison-Wesley,1962,International series of monographs on pure and applied mathematics,,,,https://cir.nii.ac.jp/crid/1130000795274597248