1. Clean Air Act Amendments of 1970, Public Law 91-604, December 31, 1970. http://www.epa.gov/air/caa/ Clean Air Act. The most current version: http://epa.gov/oar/caa/title1.html
2. Environmental and Health & Safety Management: A Guide to Compliance;Cheremisinoff,1995
3. 33/50 Program: The Final Record, EPA-745/R-99-004;U.S. Environmental Protection Agency,1999
4. Code of Federal Regulations, 40: Chapter 1, Subchapter C, Part 51, Subpart F, 51100. EXIT accessed 8 February 2009.
5. S.V. Nizich, T. Pierce, A.A. Pope, P. Carlson, and B. Barnard, National Air Pollutant Emission Trends, 1900-1996, EPA-454/R-97-011, NTIS PB98-153158, Office of Air Quality Planning and Standards, Research Triangle Park, NC, December 1997. https://www.epa.gov/air-trends/ozone-trends 1970-2013 Average annual emissions, all criteria pollutants in MS Excel - December 2013. http://www.epa.gov/ttnchie1/trends/ EPA. Air Quality Trends. http://www.epa.gov/airtrends/aqtrends.html