1. BARRON, J. (1963). Amer. J. Surg.105, 563.
2. BENNETT,.R. C., FRIEDMAN, M. H. W. and GOLIGIfER,J.C. (1963). Brit. med. J, ii, 216.
3. BLAIDSELL, P. C. (1958). Surg. Gynec. Obstet. 106, 485.
4. BROADER, J. H., GUNN, I. F. and ALEXANDER-WILLIAMS, J. (1974). Brit. J. surg. 61, 142.
5. Pnictical Proctology;BUIE, L.A.,1960