Candrilli SD, Davis KL, Iyer S. Impact of constipation on opioid use patterns, health care resource utilization, and costs in cancer patients on opioid therapy. J Pain Palliat Care Pharmacother. 2009 Sep 1;23(3):231-41.
Fleming A, Goatman KA, Sharp PF, Styles CJ, Wikes WN, Olson JA. A large scale validation of automated grading. Eur J Ophthalmol. 2009 May 1;19(3):504.