@inbook{3414530,
author={Jyotsna Nagda and Zahid H. Bajwa},
editor={Warfield, Carol A. and Bajwa, Zahid H.},
title={Chapter 4. Definitions and Classification of Pain},
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=3414530}
}