1. 1. T. C. Gray, and J. F. Nunn(1971 ) General Anaestheria, Vol. II , p.50 . Butterworths, London.
2. 2. R. S. Atkinson, G. B. Rushman, and J. A. Lee(1982 ) A Synopsis of Anaesthesia, 9th edn. pp.370 -1 . Wright PSG, Bristol.
3. 3. J. C. Snow(1982 ) Manual of Anesthesia , p.311 . Little. Brown and Co., Boston.
4. Non-Recurrent Laryngeal Nerve