Sihotang, Hotland, et al. “MODEL KONSERVASI SUMBERDAYA AIR DANAU TOBA”. Jurnal Pengelolaan Sumberdaya Alam Dan Lingkungan (Journal of Natural Resources and Environmental Management), vol. 2, no. 2, Dec. 2012, p. 65, https://doi.org/10.29244/jpsl.2.2.65.