Setiawan, Dian M. “Application of 60 70 Grade Bitumen With Layer Variations on Ballast Structures”. International Journal on Advanced Science, Engineering and Information Technology 11, no. 2 (April 24, 2021): 698–704. Accessed July 22, 2024. https://ijaseit.insightsociety.org/index.php/ijaseit/article/view/9898.