Raghunathan K, Layton JB, Ohnuma T, Shaw AD. Observational research using propensity scores. Adv Chronic Kidney Dis. 2016 Nov;23(6):367-72. doi: 10.1053/j.ackd.2016.11.010
Fleming AD, Philip S, Goatman KA, Sharp PF, Olson JA. Automated clarity assessment of retinal images using regionally based structural and statistical measures. Med Eng Phys. 2012 Sep 1;34(7):849-59. doi: 10.1016/j.medengphy.2011.09.027