Sanatkhani,M , , Pakfetrat,A , and Shirzadeh,A R . "Oral ulcers among patients referred to oral medicine department of Mashhad Dental School in a period of 6 years", Iranian Journal of Otorhinolaryngology, 21, 56, 2009, 89-94. doi: 10.22038/ijorl.2009.705