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
"Belgacem, Fethi",Elliptic boundary value problems with indefinite weights : variational formulations of the principal eigenvalue and applications,,Addison Wesley Longman,1997,Pitman research notes in mathematics series,,0582315972,,https://cir.nii.ac.jp/crid/1130282271214569344