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Melhem MF, Kunz HW, Gill TJ 3rd.Melhem MF, et al.Proc Natl Acad Sci U S A. 1993 Mar 1;90(5):1967-71. doi: 10.1073/pnas.90.5.1967.Proc Natl Acad Sci U S A. 1993.PMID: 8446616Free PMC article.