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Palevitz BA, Ash JF, Hepler PK.Palevitz BA, et al. Among authors: hepler pk.Proc Natl Acad Sci U S A. 1974 Feb;71(2):363-6. doi: 10.1073/pnas.71.2.363.Proc Natl Acad Sci U S A. 1974.PMID: 4592689Free PMC article.
Kersey YM, Hepler PK, Palevitz BA, Wessells NK.Kersey YM, et al. Among authors: hepler pk.Proc Natl Acad Sci U S A. 1976 Jan;73(1):165-7. doi: 10.1073/pnas.73.1.165.Proc Natl Acad Sci U S A. 1976.PMID: 1061112Free PMC article.