From the U.S. Geological Survey Energy Resources Program, this site provides basic information about fracking.

From Earthworks, this report gives general information on how fracking works, and potential issues with the process.

From the Pennsylvania Independent Oil & Gas Association.

From the American Petroleum Institute.

From the National Conference of State Legislatures.

An overview of hydraulic fracturing and other formation stimulation technologies for shale gas production. 2015.

History of Edward Roberts' exploding torpedo, used to increase the flow of oil.

Ever since America’s earliest oil discoveries, dynamite or nitroglycerin detonations increased a well’s production. Hydraulic fracturing came in the 1949.

Information on hydraulic fracturing and the environment from the United States Environmental Protection Agency.

This archive encompasses and documents natural gas exploration and development on a state-level, with a focus on the northern tier of Pennsylvania and the Susquehanna River Basin and Delaware River Basin respectively.

Information on the hydraulic fracturing process from Chesapeake Energy, one of the major energy providers in Pennsylvania. Via the Internet Archive.

Interactiive website from Penn State Public Broadcasting devoted to enhancing the public's understanding of the basic science surrounding drilling and hydraulic fracturing in the Marcellus Shale.

A reporting project of Pennsylvania National Public Radio stations.