共 20 条
[1]
*ACOG, 1993, FOL AC PREV REC NEUR
[2]
ADAMS MM, 1993, OBSTET GYNECOL, V82, P955
[3]
Alaimo K, 1994, DIETARY INTAKE VITAM, V258
[4]
[Anonymous], 1991, Lancet, V338, P131, DOI 10.1016/0140-6736(91)90133-A
[7]
Centers for Disease Control and Prevention (CDC), 1999, MMWR Morb Mortal Wkly Rep, V48, P325
[9]
Food and Drug Administration, 1996, FED REGISTER, V61, P8781
[10]
*FOOD NUTR BOARD N, 1990, NUTR DUR PREGN