Jhon Hardy Purba, I Putu Parmila, and Wayan Dadi. “Effect of Soilless Media (Hydroponic ) on Growth and Yield of Two Varieties of Lettuce”. Agricultural Science, Vol. 4, no. 2, Apr. 2021, pp. 154-65, http://agriscience.scientific-work.org/index.php/agriscience/article/view/58.