American Lung Association. (n.d.) Pneumonia. http://www.lungusa.org/lung-disease/pneumonia/. Accessed April 30, 2014.
Cecil RL, Goldman L, Schafer AI. 2012. Goldman's Cecil medicine (24th ed.) Philadelphia: Elsevier/Saunders
US Department of Health and Human Services. National Institutes of Health, National Heart, Lung, and Blood Institute. What is pneumonia. http://www.nhlbi.nih.gov/health/health-topics/topics/pnu. Updated March 2011. Accessed February 2016.