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Chan JC, Cheung CK, Swaminathan R, Nicholls MG, Cockram CS.Chan JC, et al. Among authors: cheung ck.Postgrad Med J. 1993 Mar;69(809):204-10. doi: 10.1136/pgmj.69.809.204.Postgrad Med J. 1993.PMID: 8497435Free PMC article.
Lau JT, Cheung CK.Lau JT, et al. Among authors: cheung ck.J Health Soc Policy. 1999;11(1):77-90. doi: 10.1300/J045v11n01_06.J Health Soc Policy. 1999.PMID: 10538432