Bjornsdottir E, Janson C, Lindberg E, Arnardottir ES, Benediktsdottir B, Garcia-Aymerich J, Carsin AE, Real FG, Toren K, Heinrich J, Nowak D, Sanchez-Ramos JL, Demoly P, Arenas SD, Navarro RC, Schlunssen V, Raherison C, Jarvis DL, Gislason T. Respiratory symptoms are more common among short sleepers independent of obesity. BMJ Open Respir Res. 2017 Aug 30;4(1):e000206. doi: 10.1136/bmjresp-2017-000206
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