Optimal Control of COVID-19 Model with Partial Comorbid Subpopulations and Two Isolation Treatments in Indonesia. European Journal of Pure and Applied Mathematics, Maryland, USA, v. 16, n. 1, p. 523–537, 2023. DOI: 10.29020/nybg.ejpam.v16i1.4666. Disponível em: https://www.ejpam.com/index.php/ejpam/article/view/4666. Acesso em: 22 dec. 2024.