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Pratt M, Macera CA, Sallis JF, O'Donnell M, Frank LD.Pratt M, et al. Among authors: macera ca.Am J Prev Med. 2004 Oct;27(3 Suppl):136-45. doi: 10.1016/j.amepre.2004.06.015.Am J Prev Med. 2004.PMID: 15450624
Pratt M, Macera CA, Wang G.Pratt M, et al. Among authors: macera ca.Phys Sportsmed. 2000 Oct;28(10):63-70. doi: 10.3810/psm.2000.10.1237.Phys Sportsmed. 2000.PMID: 20086598