Soil survey, Mercer County Pennsylvania /

por Grice, Darrell Gene, 1930-, Grubb, Robert G., Jaquish, Orin Willis, 1924-
[Washington] : Soil Conservation Service : For sale by the Supt. of Docs., U.S. Govt. Print. Off., 1971

Soil survey of Beaver and Lawrence Counties, Pennsylvania.

por Smith, Robert V., 1928-
[Washington, D.C.?] : U.S. Dept. of Agriculture, Soil Conservation Service, 1982