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
Cohen JT, Marino RJ, Sacco P, Terrin N. Association between the functional independence measure following spinal cord injury and long-term outcomes. Spinal Cord. 2012 Oct;50(10):728-33. doi: 10.1038/sc.2012.50