Beers, F. W. Atlas of the Oil Regions. Meadville, PA: Crawford County Historical Society, 1984.
Reprint of 1865 edition.
Giddens, Paul H., ed.. Pennsylvania Petroleum, 1750-1872. Harrisburg, PA: Pennsylvania Historical and Museum Commission, 1947.
Reprinted 2002 by Margaret Anne Mong.
Harris, Howard, and Blatz, Perry, eds. Keystone of Democracy: A History of Pennsylvania Workers. Harrisburg, PA: Pennsylvania Historical and Museum Commission, 1999.
A useful collection of brief vignettes on labor history, this volume offers an easy-to-use starting reference for any study of Pennsylvania workers.
This site offers a good starting point to exploring oil history on the web.
Drake Well Museum: Birthplace of the Oil Industry-1859, Titusville, Pa http://www.drakewell.org
Drake Well Museum collects, preserves, and interprets the founding of the oil industry in Pennsylvania for residents and visitors by educating its audiences about the persons, places, and events important to the development of the petroleum industry and its growth into a global enterprise.
Historic Pittsburgh: Sketches in Crude Oil. Some Accidents and Incidents of the Petroleum Development in all Parts of the Globe http://digital.library.pitt.edu/cgi-bin/t/text/text-idx?c=pitttext&vie...
Digital version of well-known text from 1896. Lots of great lithographs of the era. Sketches in Crude Oil by John McLaurin introduced many Americans to oil and the Pennsylvania oil regions.
Ida M. Tarbell, Allegheny College http://tarbell.allegheny.edu
Excellent links regarding Ida Tarbell.
Oil History http://www.petroleumhistory.org/OilHistory/OHindex.html
PBS series on the Rockefeller Family http://www.pbs.org/wgbh/amex/rockefellers/index.html
The History of Standard Oil Company http://www.history.rochester.edu/fuels/tarbell/MAIN.HTM
Digital text of Ida Tarbell's History of the Standard Oil Company.