1. Anorectal nomenclature: fundamental terminology;Wendell-Smith;Dis Colon Rectum,2000
2. Anal carcinoma and its differential diagnoses;Mitchell;Diagn Histopathol,2008
3. The anal transitional zone. A method for macroscopic demonstration;Fenger;Acta Pathol Microbiol Scand A,1978
4. The evolving treatment of anal cancer: how are we doing?;Whiteford;Arch Surg,2001