National Institute for Occupational Safety and Health. Division of Technical Services. (1978). Respiratory protection: A guide for the employee. Dept. of Health, Education, and Welfare, Public Health Service, Center for Disease Control, National Institute for Occupational Safety and Health, Division of Technical Services ; for sale by the Supt. of Docs., U.S. Govt. Print. Off..

National Institute for Occupational Safety and Health. Division of Technical Services. Respiratory Protection: A Guide for the Employee. Cincinnati, Ohio : Washington: Dept. of Health, Education, and Welfare, Public Health Service, Center for Disease Control, National Institute for Occupational Safety and Health, Division of Technical Services ; for sale by the Supt. of Docs., U.S. Govt. Print. Off., 1978.

National Institute for Occupational Safety and Health. Division of Technical Services. Respiratory Protection: A Guide for the Employee. Dept. of Health, Education, and Welfare, Public Health Service, Center for Disease Control, National Institute for Occupational Safety and Health, Division of Technical Services ; for sale by the Supt. of Docs., U.S. Govt. Print. Off., 1978.