Silaban, H. ., S. Sugita, B. Bardi, and U. . Cahyono. “PENINGKATAN PELAYANAN KERETA API PANGRANGO RELASI BOGOR-SUKABUMI”. Jurnal Penelitian Sekolah Tinggi Transportasi Darat, vol. 6, no. 2, Dec. 2015, pp. 91 - 103, http://114.141.51.86/index.php/jpsttd/article/view/18.