1. Dystocia due to the shoulders
2. C. Berkeley, V. Bonney, and D. MacLeod (1938 ): The Abnormal in Obstetrics . William Wood, Baltimore, p.477 .
3. J. C. Brash (1943 ): Cunningham's Textbook of Anatomy , 8th ed. Oxford University Press, London, p.1392 .
4. TREATMENT OF IMPACTION OF THE SHOULDER IN A VERTEX DELIVERY