Essential Nutrients and Ionic Forms
Soils: An Introduction to Soils and Plant Growth. 6th Edition. Donahue, Miller, and Shickluna.
Soil Fertility and Fertilizers, 3rd Edition. Tisdale and Nelson. 1975. Macmillan Publishing Co., Inc. New York, NY.
Soil Acidity and Liming, 2nd Edition. F. Adams. 1984. ASA, Madison, WI.
Soils and Soil Fertility. Troeh, Frederick and L.M. Thompson. 1993. Oxford University Press. New York, Ny.