- Dr M R Becklake, Respiratory Epidemiology Unit, Joint Departments of Epidemiology and Biostatistics, and of Occupational Health, McGill University, 1110 Pine Ave West, Montréal, Québec, Canada H3A 1A3.
- Received December 22, 1997
- Revision requested March 6, 1998
- Revised June 15, 1998
- Accepted June 17, 1998
- First published November 1, 1998.
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