"Masaaki Umehara,Naoya Ando","Umbilics of surfaces in the Lorentz-Minkowski 3-space",,"Results Math.",,"Vol. 78",,,2023,Sept.
"Atsufumi Honda,Naokawa Kosuke,Kentaro Saji,Masaaki Umehara,Kotaro Yamada","Symmetries of cross caps",,"TOHOKU MATH. J.",,"Vol. 75",,,2023,Mar.