SIMULIK, V. M. A theorem on the structure of a complete set of conformal-like series of conserved quantities for massless fields. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 49, n. 12, p. 1707–1711, 1997. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5177. Acesso em: 5 dec. 2025.