@inbook{3411324, author={Michael F. Cutrer and Amy O'Donnell}, editor={Warfield, Carol A. and Bajwa, Zahid H.}, title={Chapter 19. Pathophysiology of Headaches}, booktitle={Principles & Practice of Pain Medicine, 2e}, publisher={The McGraw-Hill Companies}, address={New York, NY}, year={2004}, url={accessanesthesiology.mhmedical.com/content.aspx?aid=3411324} }