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
"Hoshiro, Toshihiko",Non Analytic hypoellipticity for some operators of X2 + Y2 type,,"Institute of Mathematics, University of Tsukuba",1993,Mathematical research note,,,,https://cir.nii.ac.jp/crid/1130011528893911830