1. Possible prevention of neural tube defects by periconceptional vitamin supplementation;Smithells, R.W.; Sheppard, S.; Scorah, C.J.;Lancet,1980
2. Anencephaly in the Netherlands: a remarkable decline;Romijn, J.A.; Treffers, P.E.;Lancet,1983
3. Current trends in the incidence of neural tube defects;Windham, G.C.; Edmonds, C.D.;Pediatrics,1982
4. Nineteen year incidence of neural tube defects in area under constant surveillance;Owens, JR, McAllister; E, Harris; F, West; L.;Lancet,1981
5. Estimability and estimation in case-referment studies;0, Miettinen;Am J Epidemiol,1976