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Copp DH, Greenberg DM.Copp DH, et al.Proc Natl Acad Sci U S A. 1941 Mar 15;27(3):153-7. doi: 10.1073/pnas.27.3.153.Proc Natl Acad Sci U S A. 1941.PMID: 16588439Free PMC article.No abstract available.