Christmas Colleen, Makary Martin A, Burton John R
Department of Medicine, Division of Geriatric Medicine and Gerontology, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA.
J Am Coll Surg. 2006 Nov;203(5):746-51. doi: 10.1016/j.jamcollsurg.2006.08.006. Epub 2006 Sep 28.