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Rast JP, Litman GW.Rast JP, et al. Among authors: litman gw.Proc Natl Acad Sci U S A. 1994 Sep 27;91(20):9248-52. doi: 10.1073/pnas.91.20.9248.Proc Natl Acad Sci U S A. 1994.PMID: 7937749Free PMC article.