title: Emergency medical services system research: challenges and opportunity.
authors: Henry E
authors: HE
authors: Wang
authors: Donald M
authors: DM
authors: Yealy
mesh_terms: D004632:Emergency Medical Services / Q000458:organization & administration*; D006801:Humans; D038622:Internationality; D015279:Organizational Culture; D011785:Quality Assurance, Health Care / Q000379:methods; D012106:Research / Q000458:organization & administration*; D014481:United States