Ulum, Muhammad Miftachul, et al. “Pengaruh Sudut Kaki Terhadap Kecepatan Dan Sudut Simpangan Bola”. V-MAC (Virtual of Mechanical Engineering Article), vol. 4, no. 2, Oct. 2019, pp. 21-24, https://ejournal.unibabwi.ac.id/index.php/vmac/article/view/643.