1. Morson BC, Lockhart-Mummery HE. Anal lesions in Crohn's disease. Lancet 1959;2:1122–3.
2. Dukes CE, Galvin C. Colloid carcinoma arising within fistulae in the ano-rectal region. Ann R Coll Surg Engl 1956;18:246–61.
3. Rawls WE, Martin WJ, Spencer RJ, Hoffman HN. Perianal abscess and anorectal fistula. Minn Med 1963;46:327–31.
4. Grace RH, Harper IA, Thompson RG. Anorectal sepsis: microbiology in relation to fistula-in-ano. Br J Surg 1982;69:401–3.
5. Eykyn SJ, Grace RH. The relevance of microbiology in the management of anorectal sepsis. Ann R Coll Surg Engl 1986;68:237–9.