1. Braverman IM: Skin Signs of Systemic Disease. Philadelphia, W. B. Saunders Company, 1970, p 331
2. Spiro HM: Clinical Gastroenterology. London, Collier-MacMillan Limited, 1970, p 659
3. Verbov JL: The skin in patients with Crohn's disease and ulcerative colitis. Trans St Johns Hosp Dermatol Soc 59: 30, 1973
4. Vokurka V, Micanek B: Pyoderma in the course of ulcerative colitis. Gastroenterologia 99: 311, 1963