Deep Underground, Miles of Hidden Wildfires Rage - TIME

As far as 90 feet underground and 100 feet thick, miles of coal seams are continually burning in the U.S. and elsewhere, releasing toxic fumes that funnel up to the surface

If You Can't Stand the Heat - The Atlantic

Coal-seam fire - Wikipedia

Spontaneous combustion of coal seams in the Bengiler coal mine in Turkey

How A Fire Can Burn Underground for Thousands of Years

The Ally From Hell - The Atlantic

Coal-seam fire - Wikipedia

Photos: Wildfires Rage Across Greece - The Atlantic

Oregon firefighter warns of danger in burn areas after wildfires

Have Wildfires Ruined California's Magic? - The New York Times

Moody Planetarium, Hours & Location, Museum

One of the California wildfires grew so fast it burned the equivalent of a football field every second

Greece tames wildfire near Athens, new blazes rage in 'tough' Mediterranean summer