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.
Crain's Cleveland Business reports that Ohio does not directly track volumes of ethanes, butanes and propanes, the so-called wet gases from the Utica shale.
Producers must only provide the Ohio Department of Natural Resources with natural gas and oil production numbers.
Ohio does not require separate totals on wet gases, which will make it difficult to fully assess the financial impact of the Utcia shale, experts say.