1. Detecting Outliers in Deterministic Nonparametric Frontier Models with Multiple Outputs;Willson;Journal of Business and Economic Statistics,1993
2. Crop Diversity on Traditional Great Plains Wheat Farm;Vitale;Journal of American Society of Farm Managers and Rural Appraisers,2014
3. U .S. Department of Agriculture, National Agricultural Statistics Service. “Quick Stats.” Internet site: http://quickstats.nass.usda.gov/ (Accessed July 30, 2018).
4. U.S. Department of Agriculture, Economic Research Service. “Monthly Wheat Outlook” [2000–2013]. Internet site: http://www.ers.usda.gov/data-products/wheat-data (Accessed July 30, 2018b).