Chusaini, Muhammad, et al. “THE 50 M FREE STYLE SWIMMING STROKE SPEED IMPROVEMENT BY USING HAND PADDLE SWIM AND PARACHUTE SWIM”. JIPES - JOURNAL OF INDONESIAN PHYSICAL EDUCATION AND SPORT, vol. 6, no. 01, July 2020, pp. 7-16, https://journal.unj.ac.id/unj/index.php/jipes/article/view/17010.