RT Journal Article SR Electronic T1 Birth prevalence and recurrence rates of neural tube defects in southern Alberta in 1970-81 JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP 610a OP 611 VO 139 IS 7 A1 Ayiomamitis, A. YR 1988 UL http://www.cmaj.ca/content/139/7/610a.abstract