Al-hajj, Wadhah, Hisham Hwaiti, Anas Shamala, Hamza Al-Azazi, and Mohammed Alwesabi. “Association of Khat Chewing, Smoking, Age and Sex With Periodontal Status Among Yemeni Adults”. Brazilian Dental Science 23, no. 1 (January 31, 2020): 8 p. Accessed August 23, 2025. https://ojs.ict.unesp.br/index.php/cob/article/view/1861.