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
Rothman KJ, Wepsic JG. Side of facial pain in trigeminal neuralgia. J Neurosurg. 1974 Jan 1;40(4):514-6.