Timothy Rocke, Grains Chairperson (November 10, 1997). "World Agricultural Production: Part 1". United States Department of Agriculture. Archived from the original on August 25, 2009. Retrieved August 30, 2009.
Timothy Rocke, Grains Chairperson (November 10, 1997). "World Agricultural Production: Part 1". United States Department of Agriculture. Archived from the original on August 25, 2009. Retrieved August 30, 2009.