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Leigh JA, Signer ER, Walker GC.Leigh JA, et al. Among authors: walker gc.Proc Natl Acad Sci U S A. 1985 Sep;82(18):6231-5. doi: 10.1073/pnas.82.18.6231.Proc Natl Acad Sci U S A. 1985.PMID: 3862129Free PMC article.