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.
Pennyslvania may dominate natural gas production in the Marcellus shale for many years, according to experts.
That was the subject of an Associated Press story by Kevin Begos on Saturday.
Pennsylvania is a cost-effective place to drill and more than 2,00 wells have been drilled but not completed. Drillers are likely to complete those wells, despite lower natural gas prices.
Analysts say that Pennsylvania will likely remain the center of Marcellus drilling.
There is little Marcellus shale in Ohio. The deeper Utica shale is what drillers are after in Ohio.
Ohio and West Virginia may be better positiioned than New York to benefit from drillers going after lucrative wet gases: ethane, butane and propane.
Drillers fear that New York could impose stricter rules on drilling.
Click here to read the AP story.