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.
Local and national eco-groups say that Ohio's proposed law requiring natural gas-oil drilling companies to reveal the chemicals they use has major loopholes.
The law would allow drilling companies to declare some chemicals trade secrets that state regulators could not reveal to the public except for health professionals in a medical emergency.
Doctors who get details of a toxic chemical would not be permitted to reveal it publicly except to the patient and the immediate family.
The bill, introduced by Gov. John Kasich, was approved last week by the Ohio Senate after eight weeks of bargaining.
It is now pending in the Ohio House.
Click here to read reporter John Funk's story from Saturday's Cleveland Plain Dealer.