M. M. Oktriyanti, N. R. Palapa, R. Mohadi, and A. Lesbani, “Modification Of Zn-Cr Layered Double Hydroxide With Keggin Ion [?-SiW12O40]4- AS Cr(VI) Adsorbent”, indones. j. env. man. sus., vol. 3, no. 3, pp. 93-99, Sep. 2019.