Tweeten, Luther G., John B. Braden, Robert T. Fraley, John F. Gerber, Daryle E. Greene, Robert D. Havener, Peter Hermanson, et al. 1988. «Long-Term Viability of U.S. Agriculture». Council for Agricultural Science and Technology (CAST), junio. https://doi.org/10.62300/mgaf4r09.