@inbook{1163473915, author={Keith M. Olsen and Rachael V. McCaleb}, editor={DiPiro, Joseph T. and Yee, Gary C. and Posey, L. Michael and Haines, Stuart T. and Nolin, Thomas D. and Ellingrod, Vicki}, title={Evaluation of the Gastrointestinal Tract}, booktitle={Pharmacotherapy: A Pathophysiologic Approach, 11e}, publisher={McGraw-Hill Education}, address={New York, NY}, year={2020}, url={accesspharmacy.mhmedical.com/content.aspx?aid=1163473915} }