@inbook{1004222115, author={David L. Simel and Drummond Rennie}, title={Acute Cholecystitis}, booktitle={The Rational Clinical Examination: Evidence-Based Clinical Diagnosis}, publisher={McGraw-Hill Education}, address={New York, NY}, year={2016}, url={jamaevidence.mhmedical.com/content.aspx?aid=1004222115} }