Gray, R. B. (1956). Development of the agricultural tractor in the United States. [American Society of Agricultural Engineers].
Chicago Style (17th ed.) CitationGray, Roy Burton. Development of the Agricultural Tractor in the United States. [St. Joseph, Mich.]: [American Society of Agricultural Engineers], 1956.
MLA (9th ed.) CitationGray, Roy Burton. Development of the Agricultural Tractor in the United States. [American Society of Agricultural Engineers], 1956.
Warning: These citations may not always be 100% accurate.