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
Novick D, Montgomery WS, Aguado J, Peng X, Brugnoli R, Haro JM. Which somatic symptoms are associated with an unfavorable course in Chinese patients with major depressive disorder? Asia Pac Psychiatry. 2015 Dec;7(4):427-35. doi: 10.1111/appy.12189