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PRISMA 2009 Flow diagram.
From: Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group (2009). P referred R eporting I tems for S ystematic Reviews and M eta- A nalyses: The PRISMA Statement. PLoS Med 6(7): e1000097. doi:10.1371/journal.pmed1000097. For more information, visit www.prisma-statement.org.
