SimulikV. M. (1997) “A theorem on the structure of a complete set of conformal-like series of conserved quantities for massless fields”, Ukrains’kyi Matematychnyi Zhurnal, 49(12), pp. 1707–1711. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/5177 (Accessed: 27July2024).