CHEN, WENLI, NICHOLAS YEW LEE TAN, CHEE-KIT LOOI, BAOHUI ZHANG, and PETER SEN KEE SEOW. 2008. “HANDHELD COMPUTERS AS COGNITIVE TOOLS: TECHNOLOGY-ENHANCED ENVIRONMENTAL LEARNING”. Research and Practice in Technology Enhanced Learning 3 (3):231-52. https://rptel.apsce.net/index.php/RPTEL/article/view/2008-03008.