Kamprath,, Khasawneh,, & Sample. (1980). The role of phosphorus in agriculture: Proceedings of a symposium held 1-3 June 1976 at the National Fertilizer Development Center, Tennessee Valley Authority, Muscle Schoals, Alabama. Madison, Wisconsin: American Society of Agronomy, Crop Science of America, Soil Science Society of America.

Kamprath,, Khasawneh, and Sample. The Role of Phosphorus in Agriculture: Proceedings of a Symposium Held 1-3 June 1976 At the National Fertilizer Development Center, Tennessee Valley Authority, Muscle Schoals, Alabama. Madison, Wisconsin: American Society of Agronomy, Crop Science of America, Soil Science Society of America, 1980.

Kamprath,, Khasawneh, and Sample. The Role of Phosphorus in Agriculture: Proceedings of a Symposium Held 1-3 June 1976 At the National Fertilizer Development Center, Tennessee Valley Authority, Muscle Schoals, Alabama. Madison, Wisconsin: American Society of Agronomy, Crop Science of America, Soil Science Society of America, 1980.