1. Steck WD, Helwig EB (1965) Umbilical granulomas, pilonidal disease, and the urachus. Surg Gynecol Obstet 120:1043–1057
2. Botelho RJ (1989) Acute umbilical sepsis and pilonidal disease. J Fam Pract 29(2):205–209
3. Kasiakou SK et al (2004) Recurrent omphalitis in adults. Scand J Gastroenterol 39(10):1021–1024
4. Schoelch SB, Barrett TL (1998) Umbilical pilonidal sinus. Cutis 62(2):83–84
5. Dixit SP (1976) Pilonidal sinus of the umbilicus. Can J Surg 19(5):422–426