SIMPSON, JL, MILLS, JL, RHOADS, GG
et al. (1991). VITAMINS, FOLIC-ACID AND NEURAL-TUBE DEFECTS - COMMENTS ON INVESTIGATIONS IN THE UNITED-STATES
.
PRENATAL DIAGNOSIS, 11(8), 641-648. 10.1002/pd.1970110823
SIMPSON, JL, MILLS, JL, RHOADS, GG et al. (1991). VITAMINS, FOLIC-ACID AND NEURAL-TUBE DEFECTS - COMMENTS ON INVESTIGATIONS IN THE UNITED-STATES
. PRENATAL DIAGNOSIS, 11(8), 641-648. 10.1002/pd.1970110823