@inbook{55785114,
author={Paul Riordan-Eva, FRCOphth},
editor={Riordan-Eva, Paul and Cunningham, Emmett T.},
title={Chapter 21. Optics & Refraction},
booktitle={Vaughan & Asbury's General Ophthalmology, 18e},
publisher={The McGraw-Hill Companies},
address={New York, NY},
year={2011},
url={accessmedicine.mhmedical.com/content.aspx?aid=55785114}
}