Chesapeake Energy Corp,the Oklahoma-based firm is the No. 1 driller in Ohio.
Rig Count Interactive Map by Baker Hughes, an energy services company.
Shale Sheet Fracking, a Youngstown Vindicator blog.
The Ohio Environmental Council, a statewide eco-group based in Columbus.
Earthjustice, a national eco-group.
People's Oil and Gas Collaborative-Ohio, a grass-roots group in Northeast Ohio.
Concerned Citizens of Medina County, a grass-roots group.
No Frack Ohio, a Columbus-based grass-roots group.
Fracking: Gas Drilling's Environmental Threat by ProPublica, an online journalism site.
Pipeline, blog from Pittsburgh Post-Gazette on Marcellus shale drilling.
Allegheny Front, environmental public radio for Western Pennsylvania.
Here are some interesting tidbits about Ohio's Utica shale:
--The Utica shale in eastern Ohio is between 87 feet and 350 feet thick, says the Ohio Oil and Gas Association.
It reports that the thickest Marcellus shale in Ohio is only 62 feet thick, not thick enough for prime development.
-- The core area in the Utica shale in eastern Ohio covers about 11 million acres or 17,000 square miles, according to a report from the Ohio Department of Natural Resources'
Division of Geological Survey.