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Doblhammer G, Vaupel JW.Doblhammer G, et al.Proc Natl Acad Sci U S A. 2001 Feb 27;98(5):2934-9. doi: 10.1073/pnas.041431898. Epub 2001 Feb 20.Proc Natl Acad Sci U S A. 2001.PMID: 11226344Free PMC article.