C. A. Velasco-Benítez, O. G. Calderón-Guerrero, and J. Ramírez-Villamizar, “Functional gastrointestinal disorders in schoolchildren with chronic abdominal pain in a pediatric digestive endoscopy unit”, Univ. Salud, vol. 22, no. 1, pp. 52–57, Dec. 2019.