| Pennsylvania Railroad GG-1 Project Reference |  |
The Remarkable GG-1
Karl R. Zimmermann
Quadrant Press, Incorporated
©1977
ISBN #0-915276-16-X
Pennsy Power
Alvin F. Staufer
©1962
Library of Congress No. 62-20878
Pennsy Power II
Alvin F. Staufer
©1968
Library of Congress No. 62-20872
Pennsy Power III
Alvin F. Staufer
©1993
ISBN #0-944513-10-7
