Cita APA (7a ed.)

United States Department of Agriculture. (1998). Keys to soil taxonomy (8th ed.). USDA.

Cita Chicago Style (17a ed.)

United States Department of Agriculture. Keys to Soil Taxonomy. 8th ed. Washington,D C: USDA, 1998.

Cita MLA (8a ed.)

United States Department of Agriculture. Keys to Soil Taxonomy. 8th ed. USDA, 1998.