PIĘTKA, Marek. The estimation of the operational functions of the type exp[(Σ_{ν=1}^nβ_νs^{p_ν})λ]. Annales Mathematicae Silesianae, [S. l.], v. 4, p. 25–34, 1990. Disponível em: https://trrest.vot.pl/ojsus/index.php/AMSIL/article/view/14290. Acesso em: 7 may. 2025.