Poudel, M. P., and S.-E. . Chen. “Trends and Variability of Rice, Maize, and Wheat Yields in South Asian Countries: A Challenge for Food Security”. Asian Journal of Agriculture and Rural Development, vol. 2, no. 4, Dec. 2012, pp. 584-97, https://archive.aessweb.com/index.php/5005/article/view/624.