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Woodruff JF, Woodruff JJ.Woodruff JF, et al. Among authors: woodruff jj.Proc Natl Acad Sci U S A. 1971 Sep;68(9):2108-11. doi: 10.1073/pnas.68.9.2108.Proc Natl Acad Sci U S A. 1971.PMID: 5289370Free PMC article.