1. Weatherall DJ, Clegg JB. Inherited haemoglobin disorders: an increasing global health problem. Bull World Health Organ. 2001;79: 704-712.
2. Nagel RL, Steinberg MH. Genetics of the βS gene: origins, genetic epidemiology, and epistasis in sickle cell anemia. In: Steinberg MH, Forget BG, Higgs DR, Nagel RL, eds. Disorders of Hemoglobin. Cambridge, United Kingdom: Cambridge University Press; 2001: 711-755.
3. Livingstone FB. Frequencies of Hemoglobin Variants. New York, NY: Oxford University Press; 1985.
4. World Health Organization. Guidelines for the Control of Haemoglobin Disorders. Geneva, Switzerland: World Health Organization; 1994.
5. Leikin SL, Gallagher D, Kinney TR, Sloane D, Klug P, Rida W. Mortality in children and adolescents with sickle cell disease. Cooperative Study of Sickle Cell Disease. Pediatrics. 1989;84: 500-508.