APA (7th ed.) Citation

Gray, D. S., & Gray, A. L. (1928). Soil survey of Plymouth County, Iowa. G.P.O..

Chicago Style (17th ed.) Citation

Gray, D. S., and A. L. Gray. Soil Survey of Plymouth County, Iowa. Washington, D.C.: G.P.O., 1928.

MLA (9th ed.) Citation

Gray, D. S., and A. L. Gray. Soil Survey of Plymouth County, Iowa. G.P.O., 1928.

Warning: These citations may not always be 100% accurate.