KANG, S.; ZHANG, G.; CHENG, S. S. Periodic solutions of a class of integral equations. Topological Methods in Nonlinear Analysis, [S. l.], v. 22, n. 2, p. 245–252, 2003. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2003.038. Acesso em: 22 jul. 2024.