1. Held B.J.(1974).History of Respiratory Protective Devices in the U.S. Pre‐World War I. Lawrence Livermore National Laboratory Energy Research and Development Administration contract W‐7405‐Eng‐48.
2. Respiratory protective devices: tests for permissibility; fees;US Bureau of Mines, Department of the Interior;Fed Regist,1972
3. Respiratory protective devices: final rules and notice;National Institute for Occupational Safety and Health, US Department of Health and Human Services;Fed Regist,1995
4. Occupational Safety and Health Administration (OSHA) US Department of Labor(2016).Respiratory protection.Code of Federal Regulations Title 29 Part 1910.134.
5. Occupational Safety and Health Administration (OSHA) US Department of Labor(2016).Respiratory protection.Code of Federal Regulations Title 29 Part 1926.103.