Types of farming in Missouri / Conrad H. Hammer, Walter J. Roth and O.R. Johnson.Conrad Harold Hammar1938
Forces Affecting Wisconsin Agriculture with Resulting Types of Farming / P.E. McNall and W.J. Roth.P. McNall1935
Farm Resources and Farming Systems Needed to Meet Living Needs of Farm Families in Five Type-of-farming Areas. Prepared by Donald R. Rush and Olaf F. Larson.Donald R. Rush1942