PIĘTKA, Marek. A note on the increase of the operational function exp(λΣ_{k=1}^{n}A_{k}s^{p_k}). Annales Mathematicae Silesianae, [S. l.], v. 3, p. 107–114, 1990. Disponível em: https://journals.us.edu.pl/index.php/AMSIL/article/view/14309. Acesso em: 7 dec. 2025.