Bing found the following results
Coal - Wikipedia
Coal | Uses, Types, Pollution, & Facts | Britannica
Coal - National Geographic Society
Coal explained - U.S. Energy Information Administration (EIA)
What is coal? | U.S. Geological Survey - USGS.gov
Coal: Anthracite, Bituminous, Coke, Pictures, Formation, Uses
coal summary | Britannica
Coal Burning, Fossil Fuels, Pollution - National Geographic
Coal - IEA - International Energy Agency
Coal - Carbon, Organic Matter, Sedimentary Rock | Britannica