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.
Not all potential Marcellus shale areas are created equal.
Penn State geosciences professor Terry Engelder, nicknamed the father of Marcellus shale, once coined the term the "line of death" for the point where the Marcellus shale stops being productive in producing natural gas.
He was talking about the coal regions of Luzewrne and Lackawanna counties, according to Marcellus Drilling News.
There is a banana-shaped formation in the region that is nearly devoid of natural gas.
But geologists and drillers have been unsure how far the gasless formation might extend into surrounding areas.
There is evidence in failed newly drilled wells that it extends into Columbia County.
Yoiu can read the Marcellus Drilling News story here.