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.
Bloomberg News reports that the University of Texas will assemble a team of independent experts to review the February report on natural gas fracking, after reports said the professor who led the study is on the board of directors of a gas driller.
The new review could be completed in weeks, officials said.
Last February, the university's Energy Institute released a report on hydraulic fracturing or fracking that was proposed and presented by Charles Groat, associate director of the institute.
Reports have surfaced indicating that Groat has been on the board of Range Exploration & Production Co. since 2007, a relationship he did not disclose in the report.
The report came out saying there was no evidence of fracking causing groundwater contamination.