Soil survey of Bucks and Philadelphia Counties, Pennsylvania /

by Tompkins, Edward A.
[Washington D.C. : U.S. G.P.O.?, 1975

Soil survey, Montgomery County, Pennsylvania /

by Smith, Robert V., 1928-
[Washington D.C.] : U.S. Dept. of Agriculture, Soil Conservation Service : For sale by the Supt. of Docs., U.S. G.P.O., 1967