Pattamon Sangin, Anders J. Lindstrom, Goro Kokubugata, Minta Chaiprasongsuk, and Mingkwan Mingmuang. 2010. “Phylogenetic Relationships Within Cycadaceae Inferred from Non-Coding Regions of Chloroplast DNA”. Agriculture and Natural Resources 44 (4). Bangkok, Thailand:544-57. https://li01.tci-thaijo.org/index.php/anres/article/view/244961.