1. 4) Keighley RB, Williams NS: Pilonidal sinus. In: Surgery of the Anus, Rectum and Colon. WB Saunders, London, 1993, p467-480
2. 5) Anderson AW:Hair extracted from an ulcer. Boston Med Surg J 36:74, 1847
3. 6) Hodges RM:Pilonidal sinus. Boston Med Surg J 103:537, 1880
4. 7) Davage ON:The origin of sacrococcygeal pilonidal sinuses based on an analysis of four hundred sixty-three cases. Am J Path 30:1191-1204, 1955
5. 11) Fox SL: The origin of pilonidal sinus: with an analysis of its comparative anatomy and histogenesis. Surg Gyn Obst 60:137-149, 1935