Highway geology, Philadelphia to Pittsburgh,

by Willard, Bradford, 1894-1973
Harrisburg, Pa. [Commonwealth of Pennsylvania] Dept. of Internal Affairs, Topographic and Geologic Survey, 1939

Geology and mineral resources of Bucks County, Pennsylvania.

[Harrisburg, Pa. Commonwealth of Pennsylvania] Dept. of Internal Affairs, Topographic and Geologic Survey. 1959

Guidebook to the geology near Reading, Pa., by Bradford Willard and Donald M. Fraser.

by Willard, Bradford, 1894-1973
Harrisburg, Pa. [Commonwealth of Pennsylvania] Dept. of Internal Affairs, Topographic and Geologic Survey, 1939

Geology and mineral resources of Bucks County, Pennsylvania.

Harrisburg, Pa. : Pennsylvania Department of Property and Supplies, 1959

Guide to the highway geology from Harrisburg to Bald Eagle Mountain /

by Willard, Bradford, 1894-1973
Harrisburg, PA. : Pennsylvania Bureau of Topographic and Geological Survey, 1958

Guidebook to the geology near Reading, Pa. /

by Willard, Bradford, 1894-1973, Fraser, Donald McCoy, 1903-
Harrisburg, Pa. : Pennsylvania Dept. of Internal Affairs, Topographic and Geologic Survey, 1939

Guide to the highway geology from Harrisburg to Bald Eagle Mountain /

by Willard, Bradford, 1894-1973
Harrisburg, PA. : Pennsylvania Bureau of Topographic and Geological Survey, 1958

Geology and mineral resources of Bucks County, Pennsylvania.

Harrisburg, Pa. : Pennsylvania Dept. of Property and Supplies, 1959