Index of W2 -symmetric Semi-Riemannian Manifolds. Journal of International Academy of Physical Sciences, [S. l.], v. 24, n. 3, p. 303–311, 2020. Disponível em: http://www.iaps.org.in/journal/index.php/journaliaps/article/view/28. Acesso em: 23 oct. 2026.