1. Morbidity and Mortality Weekly Report. Improved national prevalence estimates for 18 selected major birth defects – United States, 1999–2001. In: Centers for Disease Control, editor. 2006. p. 1301–1305.
2. Parker SE, Mai CT, Canfield MA, et al. Updated national birth prevalence estimates for selected birth defects in the United States, 2004–2006. Birth Defects Res A Clin Mol Teratol. 2010;88:1008–16.
3. Stratford B. Down’s syndrome at the Court of Mantua. J Fam Med Matern Child Health. 1982;7:250–4.
4. Stratford B. Down’s syndrome: past, present and future. Harmondsworth: Penguin Books; 1989.
5. Séguin E. Traitement moral, hygiène et education des idiots et des autres enfants arriérés. Paris: Baillière; 1846.