Mohamed Abdelsalam, Abubakr, and Ibrahim Ghandour. “Prevalence of Chronic Gingivitis Among 16 Years Old Public High School Students in Khartoum”. Med Phoenix 3, no. 1 (August 15, 2018): 1-5. Accessed September 15, 2019. https://www.nepjol.info/index.php/medphoenix/article/view/20754.