Mamun , M. A. A. ., R. . Shultana, M. M. . Rana, and A. J. . Mridha. “Economic Threshold Density of Multi Species Weed for Direct Seeded Rice”. Asian Journal of Agriculture and Rural Development, vol. 3, no. 8, Aug. 2013, pp. 523-31, http://archive.aessweb.com/index.php/5005/article/view/872.