Muhtadi, Ahmad, et al. “Water Quality Conditions and Trophic Status of Lake Toba, North Sumatra,Indonesia: Implications for Lake Management”. Jurnal Pengelolaan Sumberdaya Alam Dan Lingkungan (Journal of Natural Resources and Environmental Management), vol. 16, no. 3, May 2026, p. 313, https://doi.org/10.29244/jpsl.16.3.313.