George P. Bodnar, John Herron Cox, Harold E. Earp, W. M. Hurst, R. C. Miller, E. A. Back, R. T. Cotton, H. D. Young, Dorothy Nickerson, Willis B. Combs, W. P. Carroll, F. G. Smith, Raymond L. Spangler, United States. Bureau of Agricultural Economics, United States. Department of Agriculture. National Agricultural Library. · First published 1920
