Hasni, I., D. G. A. Nursal, Y. Markolinda, M. Masrizal, and Y. Yusmayanti. “Relationship of Smoking Risk Factors and Comorbids With Covid-19 Mortality: Systematic Review and Meta-Analysis”. Jurnal Kesehatan Masyarakat Andalas, vol. 16, no. 1, Sept. 2022, pp. 3-17, doi:10.24893/jkma.v16i1.798.