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.
Pennsylvania has stricter rules on drilling for natural gas, and an industry group is O.K. with the changes.
"The legislation, while not perfect, provides the industry greater certainty to operate across Pennsylvania and takes a balanced approach," said Marcellus Shale Coalition President Kathryn Z. Klaber in a statement released on Thursday.
The new rules will ensure that Pennsylvania has "industry-leading, world-class shale gas regulations on its books," she said.
The legislation will modernize Pennsylvania's rules, will protect the environment and will enable drilling development, she said.
The new rules are part of House Bill 1950 that has been approved by the General Assembly.