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Cline MJ, Lehrer RI.Cline MJ, et al. Among authors: lehrer ri.Proc Natl Acad Sci U S A. 1969 Mar;62(3):756-63. doi: 10.1073/pnas.62.3.756.Proc Natl Acad Sci U S A. 1969.PMID: 4389749Free PMC article.