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
"Colombini, F. (Ferruccio) and 木下, 保",On the weakly hyperbolic equation of 4th order,,"Institute of Mathematics, University of Tsukuba",1999,Mathematical research note,,,,https://cir.nii.ac.jp/crid/1130000795163255424