1. Huether, C.A., Ivanovich, J., Goodwin, B.S., Krivchenia, E.L., Hertzberg, V.S., Edmonds, L.D., May, D.S., and Priest, J.H., Maternal Age Specific Risk Rate Estimates for Down Syndrome Among Live Births in Whites and Other Races from Ohio and Metropolitan Atlanta, 1970–1989, J. Med. Genet., 1998, vol. 35, pp. 482–490.
2. Sherman, S.L., Freeman, S.B., Allen, E.G., and Lamb, N.E., Risk Factors for Nondusjunction of Trisomy 21, Cytogenet. Genome Res., 2005, vol. 111, pp. 273–280.
3. Pangalos, C.G., Talbot, C.C., Jr., Lewis, J.G., Adelsberger, P.A., Petersen, M.B., Serre, J., Rethore, M.O., de Blois, M.C., Parent, P., Schinzel, A.A., et al., DNA Polymorphism Analysis in Families with Recurrence of Free Trisomy 21, Amer. J. Hum. Genet., 1992, vol. 51, pp. 1015–1027.
4. Frias, S., Ramos, S., Molina, B., del Castillo, V., and Mayen, D.G., Detection of Mosaicism in Lymphocytes of Parents of Free Trisomy 21 Offspring, Mutat. Res., 2002, vol. 52, pp. 25–37.
5. Penrose, L.S. and Smith, G.F., Down’s Anomaly, Boston: Little, Brown, 1966, Chapter 11.