SEAMAN, W. Orthogonally pinched curvature tensors and applications. MATHEMATICA SCANDINAVICA, [S. l.], v. 69, p. 5–14, 1991. DOI: 10.7146/math.scand.a-12365. Disponível em: https://www.mscand.dk/article/view/12365. Acesso em: 6 may. 2024.