SEAMAN, Walter. Orthogonally pinched curvature tensors and applications. Mathematica Scandinavica, Berkeley, CA, United States, v. 69, p. 5–14, 1991. DOI: 10.7146/math.scand.a-12365. Disponível em: https://journals.msp.org/mscand/article/view/1307. Acesso em: 24 jul. 2026.