S. Safi, S. Manzoor, U. Nasir, F. Ullah, N. Durrani, and F. Taj, “Aphthous Ulceration – Risk Factors Among Dental Students at Khyber College of Dentistry, Peshawar”, J Gandhara Med Dent Sci, vol. 8, no. 3, pp. 47–52, Jul. 2021.