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Lafferty K, Wyatt AP.Lafferty K, et al.Br Med J (Clin Res Ed). 1987 Aug 8;295(6594):392. doi: 10.1136/bmj.295.6594.392-a.Br Med J (Clin Res Ed). 1987.PMID: 3115469Free PMC article.No abstract available.