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.
Pro Publica's Lena Groeger reports on the U.S. Environmental Protection Agency's first-ever regulations on fracking and how they only deal with air pollution.
She writes that the new rules announced this week target one large source of air pollution: the burst of gas released during the first few days after a well is first tapped but before production begins.
Starting in 2015, drillers will be required to use what is called green completion technology to capture that gas.
About half of wells drilled today use that technology, but the EPA bowed to political pressure and delayed full implementation.
The new EPA rules do not deal with ground water.
You can click here to read Groeger's story.