 | Campbell, John D. (John Durward), 1905- 4n | (1) |
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 | Campbell, John D. (John Durward), 1905- 4n; Reducing cooperative cotton ginning costs in Oklahoma : three suggested ways / by John D. Campbell. Washington, D.C. : Farmer Cooperative Service, U.S. Dept. of Agriculture, 1970. | |
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