1. Douglas, R. G. and Stromme, W. B.: Operative Obstetrics. New York, Appleton-Century-Crofts, Inc., 1957, p. 427.
2. Kerr, J. M. M. and Morn, J. C.: Kerr's Operative Obstetrics. Ed. 6. Baltimore, The Williams & Wilkins Company, 1957.
3. A Fifteen-Year Study of Cesarean Section in the Woman’s Hospital in the State of New York