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Greer PB, Barnes MP.Greer PB, et al. Among authors: barnes mp.Phys Med Biol. 2007 Feb 21;52(4):1075-87. doi: 10.1088/0031-9155/52/4/014. Epub 2007 Jan 25.Phys Med Biol. 2007.PMID: 17264371