1. 2018 https://minerals.usgs.gov/minerals/pubs/commodity/asbestos/index.html#mcs
2. 2002
3. 2018 https://www.epa.gov/asbestos/us-federal-bans-asbestos
4. http://pubs.usgs.gov/circ/2006/1298/c1298.pdf
5. Kelly TD Matos GR. http://minerals.usgs.gov/minerals/pubs/historical-statistics/ 2014