LOUIE, L., and H. W. YUEN. “Physical Activity Level Among Hong Kong Secondary School Students During Physical Education Lessons and Extra-Curricular Activities: A Descriptive Study: 初步探索香港中學生於體育課及課外活動的身體活動量”. Asian Journal of Physical Education &Amp; Recreation, vol. 8, no. 2, Dec. 2002, pp. 38-42, doi:10.24112/ajper.81268.