1. S. Sato, R. Takahashi, M. Kobune, H. Gotoh. Appl. Catal. A: Gen. 356 (2009) 57-63.
2. T. Sreethawong, C. Sumaeth, S. Ngamsinlapasathian, S. Yoshikawa, J. Colloid Inter. Sci., 300 (2006) 219-224.
3. P. Kofstad, Nonstoichiometry, Diffusion and Electrical Conductivity in Binary Metal Oxide, Wiley, New York; (1972).
4. K. Tanabe, K. Mismo, Y. Ono, H. Hattori, New Solid Acids and Bases, Elsevier, New York; (1989).
5. S. Ohta, T. Kosaka, K. Sato, J. Phys: Conference Series, 225 (2010), 012043.