ERDOGAN, Mehmet. On the Ricci curvature of a hypersurface in a sphere. Mathematica Scandinavica, Berkeley, CA, United States, v. 82, n. 2, p. 186–190, 1998. DOI: 10.7146/math.scand.a-13832. Disponível em: https://journals.msp.org/mscand/article/view/996. Acesso em: 25 jul. 2026.