Dey, K.C., and V. Sharma. 2010. “Synthesis and Characterization of Transition Metals Derivatives of the Keggin Type Anion [Xn+W12O40]&Mdash; (8-N)”. Asian Journal of Chemistry 21 (3):2345-49. https://asianpubs.org/index.php/ajchem/article/view/18735.