re: "Problems ascertaining friend controls in a case-control study of lung cancer".
Jones
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Silman
A J
AJ
D016022:Case-Control Studies; D006801:Humans; D008175:Lung Neoplasms / Q000453:epidemiology; D008297:Male; D008722:Methods; D008875:Middle Aged; D012595:Scleroderma, Systemic / Q000453:epidemiology; D006113:United Kingdom / Q000453:epidemiology