Kabengele, B, et al. “Serum Vitamin D Levels in a Population of Adult Asthmatics in Kinshasa, Democratic Republic of Congo”. International Journal of Sciences: Basic and Applied Research (IJSBAR), vol. 44, no. 1, Feb. 2019, pp. 102-14, https://www.gssrr.org/JournalOfBasicAndApplied/article/view/9757.