John Stevens and his sons : Early American engineers

Author: Watkins, J. Elfreth.
Published 1892

Development of the American rail and track

Author: Watkins, J. Elfreth.
Published 1890

History of the Pennsylvania Railroad Company, 1846-l896 : in its relation to the Pennsylvania state canals and railroads and the consolidated system east and west of Pittsburgh

Author: Watkins, J. Elfreth 1852-1903.
Published 1896