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He X, Fung WK.He X, et al. Among authors: fung wk.Stat Med. 1999 Aug 15;18(15):1993-2009. doi: 10.1002/(sici)1097-0258(19990815)18:15<1993::aid-sim165>3.0.co;2-h.Stat Med. 1999.PMID: 10440882