Ong, A. N., C. C. Tan, M. T. Cañete, B. A. Lim, and J. Robles. “Association Between Metformin Use and Mortality Among Patients With Type 2 Diabetes Mellitus Hospitalized for COVID-19 Infection”. Journal of the ASEAN Federation of Endocrine Societies, vol. 36, no. 2, July 2022, pp. 133-41, doi:10.15605/jafes.036.02.20.