Simarmata, Vitri, Darwin Damanik, and Dian G Purba. “Analisis Willingness to Pay Dan Persepsi Wisatawan Terhadap Konservasi Gajah Aek Nauli Di Kabupaten Simalungun”. Jurnal Ekuilnomi 4, no. 1 (May 30, 2022): 1–13. Accessed May 10, 2024. https://jurnal.usi.ac.id/index.php/ekuilnomi/article/view/332.