ANDRES, Jan; KRAJC, Bohumil. Unified approach to bounded, periodic and almost periodic solutions of differential systems. Annales Mathematicae Silesianae, [S. l.], v. 11, p. 39–53, 1997. Disponível em: https://trrest.vot.pl/ojsus/index.php/AMSIL/article/view/14183. Acesso em: 7 may. 2025.