1) Valenti, C., Schutta, E.J. and Kehaty, T. (1968): Prenatal diagnosis of Down syndrome. Lancet, 2, 220.
2) Leschot, N.J., Verjaal, M. and Treffers, P.E. (1985): Risks of midtrimester amniocentesis; assessment in 3000 pregnancies. Br. J. Obstet. Gynaecol. 92, 804-807.
3) National Institute of Child Health Development National Registry for Amniocentesis Study Group (1976): Midtrimester amniocentesis for prenatal diagnosis: safety and accuracy. JAMA 236, 1471-1476.
4) Tabor, A., Philip, J., Madsen, M.I., Bang, J., Obel, E.B. and Norgaard-Pedersen, B. (1986): Randmized controlled trial of genetic amniocentesis in 4,606 low-risk women. Lancet, 1, 1287-1293.
5) Goldberg, J.D. and Norton, M.E. (2001): Prenatal diagnostic techniques. In: The unborn patient, 3rd edition (Harrison, M.R. ed.), pp. 125-148, W.B. Saunders Company, Philadelphia.