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Voynick IM, Fruton JS.Voynick IM, et al.Proc Natl Acad Sci U S A. 1971 Feb;68(2):257-9. doi: 10.1073/pnas.68.2.257.Proc Natl Acad Sci U S A. 1971.PMID: 5277065Free PMC article.