@inbook{1115518843, author={Michael Varner and Antonella Palla and Kathleen Digre}, editor={Pacheco, Luis D. and Saade, George R. and Hankins, Gary D.V.}, title={Headache and Pregnancy}, booktitle={Maternal Medicine}, publisher={McGraw-Hill Education}, address={New York, NY}, year={2015}, url={obgyn.mhmedical.com/content.aspx?aid=1115518843} }