1. How to Critically Read the GI Epidemiology Literature
Joe West, Timothy R. Card, Kate M. Fleming 
Gastroenterology 
Volume 145, Issue 3, Pages (September 2013)
DOI: /j.gastro
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2. Figure 1
Oxford Centre for Evidence-Based Medicine Levels of Evidence Table.
Gastroenterology  , DOI: ( /j.gastro )
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3. Gastroenterology 2013 145, 496-499DOI: (10.1053/j.gastro.2013.06.050)
Copyright © 2013 AGA Institute Terms and Conditions