"M. Umehara,K. Yamada","Hypersurfaces with light-like points in a Lorentzian manifold",,"Journal of Geometric Analysis",,"Vol. 29",,"pp. 3405-3437",2019,Dec.
"S. Akamine,M. Umehara,K.Yamada","Space-like maximal surfaces containing entire null lines in Lorentz-Minkowski 3-space",,"Proc. Japan Acad. Ser.A, Math. Sci.",,"Vol. 95","No. 9","pp. 97-102",2019,Oct.
"Atsufumi Honda,Naokawa Kosuke,Masaaki Umehara,Kotaro Yamada","Isometric realization of cross caps as formal power series and its applications",,"Hokkaido Mathematical Journal",,"Vol. 48","No. 1","pp. 1-44",2019,Feb.
"Shoichi Fujimori,Yu Kawakami,Masatoshi Kokubu,Wayne Rossman,Masaaki Umehara,Kotaro Yamada","Exceptional constant mean curvature one  catenoids in de Sitter 3-space",,,,,,,2019,Jan.