Maternal serum alpha-fetoprotein levels in multiple pregnancy. by Wald, N, Barker, S, Peto, R, Brock, D, Bonnar, J

Maternal serum alpha-fetoprotein and previous neural tube defects. by Wald, N, Barker, S, Peto, R, Brock, D, Bonnar, J

Effect of gestational age on screening for neural-tube defects by maternal plasma-A.F.P. measurement. by Brock, D, Scrimgeour, J, Bolton, A, Wald, N, Peto, R, Barker, S