1. Umbilical hernia;Crump;J Pediatr,1952
2. Umbilical hernia. A retrospective study;Jackson;Calif Med,1970
3. Observations on the disappearance of umbilical hernias in infancy and childhood;Heifetz;Surg Gynecol Obstet,1963
4. The natural history of umbilical hernia;Walker;Clin Pediatr,1977
5. Repair of umbilical hernias in childhood to prevent adult incarceration;Haller;Am Surg,1971