 | Callahan, John Conrad, 1923- 2n | (2) |
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 | Callahan, John Conrad, 1923- 2n; Economic returns associated with fifty nonindustrial, private woodlands in Indiana / John C. Callahan. Lafayette, Ind. : Purdue University Agricultural Experiment Station, 1966. | |
| Callahan, John Conrad, 1923- 2n; Economic aspects of commercial outdoor recreation enterprises in Southern Indiana / John C. Callahan and Douglas M. Knudson. Lafayette, Ind. : Purdue University Agricultural Experiment Station, 1966. | |
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