Coal and Carbon Atlas:
Crelling, J.C., and Rimmer, S.M., 2015, Crelling's Petrographic Atlas of Coals and Carbons. Southern Illinois University Carbondale. http://www.coalandcarbonatlas.siu.edu/
TSOP (The Society for Organic Petrology):
http://www.tsop.org/
USGS Organic Petrology Homepage:
http://energy.usgs.gov/Coal/OrganicPetrology.aspx
ICCP (International Committee for Coal and Organic Petrology):
http://www.iccop.org/
Crelling, J.C., and Rimmer, S.M., 2015, Crelling's Petrographic Atlas of Coals and Carbons. Southern Illinois University Carbondale. http://www.coalandcarbonatlas.siu.edu/
TSOP (The Society for Organic Petrology):
http://www.tsop.org/
USGS Organic Petrology Homepage:
http://energy.usgs.gov/Coal/OrganicPetrology.aspx
ICCP (International Committee for Coal and Organic Petrology):
http://www.iccop.org/