1. Zwemer TJ. Mosby's Dental Dictionary. St. Louis: Mosby, Inc., 1998; 245.
2. Regezi JA, Sciubba JJ, Connective tissue lesions, Oral Pathology: Clinical Pathologic Correlations. St. Louis: Saunders, 2003; 157–181.
3. Rateitschak KH, Rateitschak EM, Color Atlas of Dental Medicine, 2nd ed. Stuttgart: Georg Thieme Verlag, 1989; 117,281.