1. From balloon to black hawk. Part I: The origins;Lam;U.S. Army Aviation Digest,1981
2. Air evacuation prior to World War II;Shirley,1956
3. Landmarks in the Development of Patient Transport Systems in Emergency Transport of the Perinatal Patient;Chou,1989
4. Air evacuation: An historical review;Guilford;Aviat Med,1947
5. The use of the aeroplane in the medical services in war;Munro,1923