N. Nawiyah, R. Jonuarti, Y. Darvina, R. Hidayat, and S. Syafri, “Analysis of Raw Natural Montmorillonite (MMT) from Marapi Volcanic Ash and Its Potential as an Adsorbent”, Department of Physics, Universitas Negeri Padang, vol. 3, no. 1, Mar. 2025.