@inbook{1140330695, author={Michael Harrigan and Ana C. G. Felix}, editor={Tintinalli, Judith E. and Stapczynski, J. Stephan and Ma, O. John and Yealy, Donald M. and Meckler, Garth D. and Cline, David M.}, title={Headache}, booktitle={Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 8e}, publisher={McGraw-Hill Education}, address={New York, NY}, year={2016}, url={accessemergencymedicine.mhmedical.com/content.aspx?aid=1140330695} }