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Lawther RP, Hatfield GW.Lawther RP, et al.Proc Natl Acad Sci U S A. 1980 Apr;77(4):1862-6. doi: 10.1073/pnas.77.4.1862.Proc Natl Acad Sci U S A. 1980.PMID: 6154938Free PMC article.