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.
An expert on the natural-gas boom is again facing criticism over his ties to industry and the lack of transparency in how he presents work to the public, the Associated Press reported this week.
Timothy Considine was the lead author of a shale-gas report recently issued by the University of Buffalo and a previous report from Penn State University.
Critics say both reports presented research in misleading ways and failed to fully disclose funding sources.
Considine is now at the University of Wyoming.
He has gotten funding from the Marcellus Shale Coalition, the Wyoming Mining Association, the American Iron and Steel Institute and the American Petroleum Institute.
His work at Buffalo have been criticized by the Public Accountability Initiative, a Buffalo-based non-profit group.