TARCHAŁA, Katarzyna; WALCZAK, Paweł. Multi ping-pong and an entropy estimate in groups. Annales Mathematicae Silesianae, [S. l.], v. 32, p. 313–318, 2018. Disponível em: https://trrest.vot.pl/ojsus/index.php/AMSIL/article/view/13929. Acesso em: 7 may. 2025.