Pimpalak Wongapiwatkul และ Bhinyo Panijpan. (2011) Development of an inquiry-based learning unit to promote high-school students' conceptual understanding of earth geometry and trigonometry. Mahidol University:ม.ป.ท.Pimpalak Wongapiwatkul และ Bhinyo Panijpan. 2011. Development of an inquiry-based learning unit to promote high-school students' conceptual understanding of earth geometry and trigonometry. ม.ป.ท.:Mahidol University;Pimpalak Wongapiwatkul และ Bhinyo Panijpan. Development of an inquiry-based learning unit to promote high-school students' conceptual understanding of earth geometry and trigonometry. ม.ป.ท.:Mahidol University, 2011. Print.