@inbook{1131932332, author={Paul G. Mathew and Huma Sheikh}, editor={Bajwa, Zahid H. and Wootton, R. Joshua and Warfield, Carol A.}, title={Approach to the Patient with Headache}, booktitle={Principles and Practice of Pain Medicine, 3e}, publisher={McGraw-Hill Education}, address={New York, NY}, year={2016}, url={accessanesthesiology.mhmedical.com/content.aspx?aid=1131932332} }