1. U. S. Public Health Service, "Sampling Microbiological Aerosols," Communicable Disease Center, Technical Development Laboratories, and the Physical Defense Division, U. S. Army Chemical Corps; Public Health Service Publication No. 686,1959
2. National Aeronautics and Space Administration, “NASA Standards for Clean Rooms and Work Stations for the Microbially Controlled Environment,” NHB 5340.2, August 1967.