ETEMAD, Dehkordy A. First eigenvalue of the Laplace operator and mean curvature. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 60, n. 7, p. 1000–1003, 2008. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3217. Acesso em: 5 dec. 2025.