Recent trends in the incidence of multiple births and associated mortality.

nork Botting, B J, Davies, I M, Macfarlane, A J
Argitaratua 1987

Congenital anterior abdominal wall defects in England and Wales 1987-93: retrospective analysis of OPCS data.

nork Tan, K. H., Kilby, M. D., Whittle, M. J., Beattie, B. R., Booth, I. W., Botting, B. J.
Argitaratua 1996