Iskandar, Aris. “Pengaruh Metode Circuit Training Dan Fartlek Training Serta Kapasitas Vital Paru Terhadap Kapasitas Volume Oksigen Maximal”. Unimuda Sport Journal : Jurnal Pendidikan Jasmani, vol. 4, no. 1, Sept. 2023, pp. 44-64, https://e-journal.unimudasorong.ac.id/index.php/unimudasportjournal/article/view/972.