FIACCA, Antonella; NIKODEM, Kazimierz; PAPALINI, Francesca. Hull-concave set-valued functions. Annales Mathematicae Silesianae, [S. l.], v. 8, p. 211–216, 1994. Disponível em: https://trrest.vot.pl/ojsus/index.php/AMSIL/article/view/14236. Acesso em: 7 may. 2025.