Burhan, Zakir, and Lalu Yoga Vandita. “The Effect of Imagery Exercise and Progressive Muscle Relaxation on Anxiety and Concentration in Soccer Athletes”. Prisma Sains : Jurnal Pengkajian Ilmu dan Pembelajaran Matematika dan IPA IKIP Mataram 9, no. 2 (December 30, 2021): 220–224. Accessed August 16, 2025. https://e-journal3.undikma.ac.id/index.php/prismasains/article/view/4280.