1VertucciFJ. Root canal morphology of the mandibular premo- lars[J]. J Am Dent Assoc, 1978, 97(1) : 47.
2Tzu- Yi Lu, Shue- Fen Yang, Sheng- Fang Pai, Complicat ed root canal morphology of mandibular first premolar in a Chinese population using the cross section method [J]. J Endod,2006,10(32) : 932-936.
3Saunders W, Saunders E. Convention endodontics and the op- erating microscope [J]. Dent ClinNorthAm, 1997, 41(3): 415.