Fedorchuk VM, Fedorchuk VI. On functional bases of the first-order differential invariants for non-conjugate subgroups of the Poincaré group P(1,4). Ann. Univ. Paedagog. Crac. Stud. Math. [Internet]. 2008 Nov. 8 [cited 2026 Oct. 31];7:41-50. Available from: https://studmath.uken.krakow.pl/article/view/13268