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.
Last week ,ProPublica hosted a program on The Perils and Promises of Fracking, in cooperation with New York City's Tenement Museum.
ProPublica -- it calls itself journalism in the public interest -- was one of the first groups to write extensively about fracking or hydraulicalic fracturing to reach natural gas.
Social media producer Blair Hickman has broken the 90-minute discussion into a four-takeaway video.
You can read and view Hickman's summary at www.propublica.org/article/four-big-takeaways-from-this-weeks-fracking-talk.