1. Gross. R.E.: The Surgery of Infancy and Childhood; Its Principles and Techniques . Philadelphia. W. B. Saunders Company, 1953, pp. 611, 623.
2. Snyder, W.H., Jr., Hastings, T.N. and Pollock, W.: Retroperitoneal tumors. In Pediatric Surgery, vol. 2. Chicago, Year Book Medical Publishers, Inc., 1962, p. 877.
3. Congenital malignant tumors