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.
Physicians Scientists and Engineers for Healthy Energy released its reaction to new U.S. Environmental Protection Agency rules on hydraulical fracturing or fracking for natural gas.
The non-profit group, based in Ithica, N.Y., called the new air rules "too little, too late" in a statement released on Monday.
Shale gas emissions and leaks are significant and escaping methane gas is worse than carbon dioxide in its ability to change the climate, said professors Anthony Ingraffea and Robert Howarth of Cornell University.
More should have been done to reduce methane emissions from natural gas drilling, they said.
The new federal rules don't go into effect until Jan. 1, 2015.;
For more information, go to www.psehealthyenergy.org.