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 last-minute provision dropped into Pennsylvania's state budget bill and signed by Gov. Tom Corbett would block drilling for natural gas in parts of southeast Pennstlvania.
The provision would block drilling in the South Newark Basin that stretches from New Jersey through Bucks, Montgomery and Berks counties in Pennsylvania.
Lawmakers are puzzled by the development and drillers are drying foul, says the Pittsburgh Post Gaxette.
The moratorium would expire in 2018.
Drilling cannot begin there until the Delaware River Basinc Commission approves drilling rules.
A study by the U.S. Geological Survey indicates that the basin contains both shale and coal bed methane deposits.
It says the South Newark Basin contains at least 363 billion cubic feet of natural gas and the agency's best estimate is that it contains 876 billion cubic feet.
Click here to read an account of what happened.