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.
A new Pennsylvania survey shows that 49 percent of respondents support Marcellus shale drilling, but that 63 percent feel more rules are needed to govern drilling.
The survey was done by pollster Joseph Morris of Mercyhurst College in Erie.
The survey also indicated that shale drilling may not be a key issue in the Pennsylvania's governor race.
Click here to read the full story from NPR's StateImpact Pennsylvania.