Silapanuntakul, S., P. Intrarasaksit, P. Vatanasomboon, and K. Tantrakarnapa. “Uptake of Copper and Zinc in Lettuce (Lactuca sativa L.) Planted in Sida Soil and Lignite Bottom Ash Mixtures”. Asian Health, Science and Technology Reports, vol. 25, no. 3, July 2017, pp. 31-42, https://ph03.tci-thaijo.org/index.php/ahstr/article/view/1705.