1. 1G.T. Spencer, W.D. Wylie, and H.C. Churchill-Davidson (1966 ). InA Practice of Anaesthesia , 2nd edn , p.405 . London: Lloyd-Luke Ltd.
2. 2A. Gilston, and L. Resnekov (1971 ). Cardio-Respiratory Resuscitation , 1st edn. , p.157 . London: William Heinemann Medical Books Ltd.