OLBRYŚ, Andrzej. On a separation theorem for delta-convex functions. Annales Mathematicae Silesianae, [S. l.], v. 34, n. 1, p. 133–141, 2020. Disponível em: https://journals.us.edu.pl/index.php/AMSIL/article/view/13638. Acesso em: 18 apr. 2025.