Courtney DM, Kline JA, Kabrhel C, Moore CL, Smithline HA, Nordenholz KE, Richman PB, Plewa MC. Clinical features from the history and physical examination that predict the presence or absence of pulmonary embolism in symptomatic emergency department patients: results of a prospective, multicenter study. Ann Emerg Med. 2010 Apr; 55(4):307-315.e1.