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.
Matt Damon intends to star in The Promised Land, an anti-fracking movie that is set to begin filming later this month in western Pennsylvania.
Damon, will star in the film that he also co-wrote.
Little is known about the movie. The Internet Movie Data Base says only that "a salesman experiences life-changing events after arriving in a small town."
Others starring in the film include John Krasinski and Rosemarie DeWitt.
The film will be directed by Gus Van Sant, who did Good Will Hunting, Milk and Finding Forester.
Filming is expected to take place near Pittsburgh from late April to early June.