Firoz, Z., M. Rouf, S. Mozumder, and M. Zaman. “Effect of Sowing and Harvesting Time on the Growth and Quality of Lettice”. Bangladesh Journal of Agricultural Research, vol. 32, no. 4, Oct. 2008, pp. 587-92, https://banglajol.info/index.php/BJAR/article/view/1277.