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.
Exxon Mobil Corp. has announced plans to boost its holdings in the Bakken shale of North Dakota and Montana by 50 percent.
The company said it intends to spent $1.6 billion to increase its oil-rich Bakken holdings.
It intends to buy all of the Bakken shale assets held by Denbury Resources Inc. for cash. Denbury will also receive Exxon's interest in two oil fields in Wyoming and Texas.
Exxon will acquire 196,000 acres with the purchase. That will bring its Bakken holdings to nearly 600,000 acres.
The Exxon acreage is expected to produce 15,000 barrels per day in the second half of 2012.
That production will increase with additional wells.
The deal increase's Exxon's U.S. oil production by 3 percent.