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.
Inside Climate News reports that two test wells were drilled earllier this year outside Los Angeles.
The wells, drilled by Plains Exploration and Production, were aimed at extracting oil from the Monterey shale about 7,500 feet below the ground.
The wells are in the aging Inglewood Oil Field that has been operating since the 1920s.
Last year, PXP reached an agreement with local and state agencies and neighbors to clean up the pollution from its urban Inglewood operation.
Fracking is a big and contentious issue in California.
It takes large volumes of water, a commodity that is in great demand in California.
California contains nearly two thirds of the shale deposits in the United States, according to the U.S. Energy Information Administration.
This battle is just getting under way.