Lukkhana Benjawan, Seung-Hwan Lee, & Thammarat Koottatep. (2008). Nitrogen Removal in Duckweed-Based Ponds with Effluent Recirculation. Agriculture and Natural Resources, 42(4), 767–775. retrieved from https://li01.tci-thaijo.org/index.php/anres/article/view/244514