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Liu YP, Sun L, Wu XF, Yang Y, Zhang CT, Zhou HL, Quan XQ.Liu YP, et al. Among authors: zhou hl.BMJ Open. 2017 Nov 28;7(11):e018853. doi: 10.1136/bmjopen-2017-018853.BMJ Open. 2017.PMID: 29187417Free PMC article.