Agustianingsih, S., R. Reorita, and R. Renny. “Optimal Control for SIR Model With The Influence of Vaccination, Quarantine and Immigration Factor”. Jurnal Matematika, Statistika Dan Komputasi, vol. 16, no. 3, Apr. 2020, pp. 311-24, doi:10.20956/jmsk.v16i3.6942.