- Dr GH Schierhout, Department of Epidemiology and Public Health, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK. Telephone 0044 0171 813 8395; fax 0044 0171 242 2723.
- Received March 25, 1997
- Revised July 4, 1997
- Accepted July 14, 1997
- First published January 1, 1998.
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