RWAT, Solomon Isa; AHMAD, Noor Atinah Ahmad. Backward Bifurcation and Hysteresis in a Mathematical Model of COVID19 with Imperfect Vaccine. MATEMATIKA, [S. l.], v. 39, n. 1, p. 87–99, 2023. DOI: 10.11113/matematika.v39.n1.1458. Disponível em: https://matematika.utm.my/index.php/matematika/article/view/1458. Acesso em: 22 may. 2024.