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Hanson RD, Hohn PA, Popescu NC, Ley TJ.Hanson RD, et al. Among authors: ley tj.Proc Natl Acad Sci U S A. 1990 Feb;87(3):960-3. doi: 10.1073/pnas.87.3.960.Proc Natl Acad Sci U S A. 1990.PMID: 2300587Free PMC article.