A fixed-point approach to a multi-group SEIRV epidemic model. Journal of Prime Research in Mathematics, [S. l.], v. 18, n. 2, p. 144 – 151, 2022. Disponível em: https://jprm.sms.edu.pk/index.php/jprm/article/view/203. Acesso em: 3 feb. 2026.