Hartana. “EKSISTENSI PERUSAHAAN DI SEKTOR PERTAMBANGAN BATUBARA”. Jurnal Pacta Sunt Servanda 4, no. 1 (March 1, 2023): 110-119. Accessed May 7, 2024. https://ejournal2.undiksha.ac.id/index.php/JPSS/article/view/1887.