作者 | Joseph Benjamin Shepherd / Leonard G. Schoenleber / W. H. Hosterman / H. M. Tysdal / R. E. Wagner / W. J. Sweetman / H. G. Wiseman / C. G. Melin / L. A. Moore / Mason August Hein / United States. Agricultural Research Administration / United States. Bureau of Dairy Industry / United States. Bureau of Plant Industry, Soils, and Agricultural Engineering / United States. Department of Agriculture. Production and Marketing Administration |