References:

Bockosh, George, Fotta Barbara, and McKewan William ”Employment, Production, and Fatality trends in the U. S. Coal Mining Industry” CoalAge 1 Oct. 2002 http://coalage.com/ar/coal_employment_production_fatality/index.htm

“United States Bureau of Mines” Evaluation of Several Natural Gamma Radiation Systems-A Preliminary Study
http://www.cdc.gov/niosh/mining/pubs/pdfs/ic9434.pdf
 

Geosteering data collected
www.msha.gov/webcasts/coal2004/REDZONE2.pdf
www.msha.gov/fatals/fab.htm

www.msha.gov/Accident_Prevention/NewTechnologies/Initiatives/ProximityProtection/Proximityprotection.asp