1. Schaaf, Horning, and Kane, “Design and Initial Operation of a Low Density Supersonic Wind Tunnel,” presented at Heat Transfer and Fluid Mechanics Institute, Berkeley, June, 1949 and published by Am. Soc. Mech. Engrs.
2. S. Dushman,Scientific Foundations of Vacuum Technique(John Wiley & Sons, Inc., New York, 1949).