Soil survey manual - "United States, Government of..... Plant Industry. Soils and Agricultural Engineering (Bureau of...) (Soil Survey Staff)"; "United States, Government of..... Plant Industry. Soils and Agricultural Engineering (Bureau of...) (Soil Survey Staff)" (Washington Bureau of Soils and Agricultural Engineering, 1966)
"United States, Agriculture (Department of...), Handbooks, 18."
Keywords: Agriculture