title: Mid-year report ... growth of twin-engine helicopters as a percentage of the market.
authors: H M
authors: HM
authors: Collett
mesh_terms: D000401:Aircraft / Q000706:statistics & numerical data*; D000552:Ambulances / Q000706:statistics & numerical data*; D003625:Data Collection; D004636:Emergency Service, Hospital / Q000639:trends*; D014481:United States