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Troeh, Frederick R., and Louis M. (Louis Milton) Thompson. Soils and Soil Fertility. 6th ed. Ames, Iowa: Blackwell Pub., 2005. 存档副本. [2012-04-26]. (原始内容存档于2014-10-26).
Troeh, Frederick R., and Louis M. (Louis Milton) Thompson. Soils and Soil Fertility. 6th ed. Ames, Iowa: Blackwell Pub., 2005. 存档副本. [2012-04-26]. (原始内容存档于2014-10-26).