1
2
Author: Cutbush, James, 1788-1823.
Published 1812
Record Source: Published Materials
Subjects and Genres: '; ...Specific gravity....
Book
3
Author: Wakefield, Manville B.
Published 1965
Record Source: Published Materials
Subjects and Genres: '; ...Railroads, Gravity History....
Book
4
5
Author: Graeff, Arthur D. 1899-1969.
Published 1976
Record Source: Published Materials
Subjects and Genres: '; ...Railroads, Gravity Pennsylvania Berks County....
Book
7
Published 2002
Record Source: Published Materials
Subjects and Genres: '; ...Railroads, Gravity Pennsylvania Wayne County....
Book
10
Published 2004
Record Source: Published Materials
Subjects and Genres: '; ...Railroads, Gravity Pennsylvania Wayne County....
Book
15