1. Morgagni, J. B.: The Seats and Causes of Diseases (translated by B. Alexander). London: A. Millar, T. Cadell and Johnson and Payne, 1769, vol. 2, book 3, pp. 428-429. (Cited by Robertson, H. E.: Hydronephrosis and Pyelitis of Pregnancy. Philadelphia: W. B. Saunders Co., 1944.)
2. Urological Diseases of Pregnancy;Crabtree,1942
3. Robertson, H.E.: Loc. cit.1 (Over 900 references.)