Lukkhana Benjawan, Seung-Hwan Lee and Thammarat Koottatep (2008) “Nitrogen Removal in Duckweed-Based Ponds with Effluent Recirculation”, Agriculture and Natural Resources. Bangkok, Thailand, 42(4), pp. 767–775. available at: https://li01.tci-thaijo.org/index.php/anres/article/view/244514 (accessed: 17 September 2026).