CHOQUET-BRUCHAT, Y.; YORK, J. W. On H. Friedrich’s formulation of the Einstein equations with fluid sources. Topological Methods in Nonlinear Analysis, [S. l.], v. 18, n. 2, p. 321–335, 2001. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2001.037. Acesso em: 3 jul. 2024.