"Udo Hertrich-Jeromin,Yshihiko Suyama,Masaaki Umehara,Kotaro Yamada","A duality for conformally flat hypersurfaces",,"Beitraege zur Algebra und Geometrie / Contributions to Algebra and Geometry",,"Vol. 56","No. 2","  655-676",2015,Oct.
"梅原雅顕,山田光太郎","曲線と曲面・微分幾何的アプローチ（改訂版）",,,"裳華房",,,,2015,Feb.
"Shoichi Fujimori,Young Wook  Kim,Sung-Eun  Koh,Wayne Rossman,Heayong  Shin,Masaaki Umehara,Kotaro Yamada,Seong-Deog Yang","Zero mean curvature surfaces in Lorentz-Minkowski 3-space and 2-dimensional fuluid mechanics",,"Math. J. Okayama Univ.",,"Vol. 57","No. 1","pp. 173-200",2015,Jan.
"Shoichi Fujimori,Young Wook  Kim,Sung-Eun  Koh,Wayne Rossman,Heayong  Shin,Masaaki Umehara,Kotaro Yamada,Seong-Deog Yang","Zero mean curvature surfaces in Lorentz-Minkowski 3-space which change type across a light-like line",,"OSAKA JOURNAL OF MATHEMATICS",,"Vol. 57","No. 1","pp. 285-297",2015,Jan.
"Hasegawa, M.,Honda, A.,Naokawa, K.,Saji, K.,Umehara, M.,Kotaro Yamada","Intrinsic properties of surfaces with singularities",,"International Journal of Mathematics",,"Vol. 26","No. 4",,2015,