Munthe, Muhtar Ardansah, et al. “Ecotourism Strategy and Potential of Delleng Simpon, Ulumerah, Pakpak Bharat Regency”. Jurnal Pijar Mipa, vol. 19, no. 2, Mar. 2024, pp. 280-7, doi:10.29303/jpm.v19i2.6543.