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.
Democrats in New Jersey are trying again to prohibit hydraulic fracturing or fracking for natural gas.
Democrats control the Assembly 48-32 and the Senate 24-16, but might need 54 members in the Assembly and 27 in the Senate to override Christie vetoes.
In August, Gov. Chris Christie, a Republican, vetoed a ban and lodged a moratorium. The lawmakers agreed to the one-year moratorium last month. It expires in January 2013.
The Utica shale extends under two counties in northwest New Jersey, although no companies are drilling into that formation. That area provides about half of New Jersey's drinking water.
Christie has declined comment on the latest legislative move.