1. A. R. Steven . in Cabot's “Urology,” 1924.
2. B. L. Keye . Keyes “Urology,” 1928.
3. Thomson Walke . Genito-urinary Surg., 1914.
4. Chas. H. Chetwoo . “The Practice of Urology and Syphilology,” 1927.
5. Bryant . and Buc . Amer. Practice of Surg 1911.