United States. Bureau of Plant Industry. (1938). Correlations between annual precipitation and yield of spring wheat in the Great Plains. [s.n.].
Chicago Style (17th ed.) CitationUnited States. Bureau of Plant Industry. Correlations Between Annual Precipitation and Yield of Spring Wheat in the Great Plains. [Washington]: [s.n.], 1938.
MLA (9th ed.) CitationUnited States. Bureau of Plant Industry. Correlations Between Annual Precipitation and Yield of Spring Wheat in the Great Plains. [s.n.], 1938.
Warning: These citations may not always be 100% accurate.