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Schaffer FM, Palermos J, Zhu ZB, Barger BO, Cooper MD, Volanakis JE.Schaffer FM, et al.Proc Natl Acad Sci U S A. 1989 Oct;86(20):8015-9. doi: 10.1073/pnas.86.20.8015.Proc Natl Acad Sci U S A. 1989.PMID: 2573059Free PMC article.