Roni, M., M. Zakaria, M. Hossain, and M. Siddiqui. “Effect of Plant Spacing and Nitrogen Levels on Nutritional Quality of Broccoli (Brassica Oleracea L.)”. Bangladesh Journal of Agricultural Research, vol. 39, no. 3, Feb. 2015, pp. 491-04, doi:10.3329/bjar.v39i3.21992.