Sutopo, W., S. N. Bahagia, A. Cakravastia, and T. Arisamadhi. “A Buffer Stock Model to Ensure Price Stabilization and Availability of Seasonal Staple Foods under Free Trade Considerations”. Journal of Engineering and Technological Sciences, vol. 44, no. 2, Sept. 2013, pp. 128-4, doi:10.5614/itbj.eng.sci.2012.44.2.3.