Priyanto, Kurniawan Edi, and Sumardiyono Sumardiyono. “Activities of Brain Gymnastics Against Enhancement of Cognitive Function in the Elderly”. Journal of Global Research in Public Health 6, no. 1 (June 3, 2021): 25-30. Accessed December 2, 2021. https://jgrph.org/index.php/JGRPH/article/view/305.