1. Morphology of the pulp cavity of the permanent teeth
2. Microscopic Measurements of Root Canal Preparations Following In strumentation
3. W. Hess(1925 ) The anatomy of the root canals of the teeth of the permanent dentition , p.34 . John Bale, Sons and Danielsson Ltd, London.
4. J.I. Ingle, and E.E. Beveridge(1976 ) Endodontics , 2nd end, pp.101 -213 , Lea and Febiger, Philadelphia.
5. Effect of instrumentation on the shape of the root canal