1. D. I. Ryabchikov and V. A. Ryabukhin, The Analytical Chemistry of Rare-Earth Elements and Yttrium (Nauka, Moscow, 1966) [in Russian].
2. S. S. Korovin, G. V. Zimina, A. M. Reznik, et al., Rare and Trace Elements. Chemistry and Technology (MISIS, Moscow, 1996), Vol. 1 [in Russian].
3. S. B. Jundhale and C. D. Lockhande, Mater. Chem. Phys. 27, 265 (1991).
4. N. D. Gaikwad and C. H. Bhosale, Mater. Chem. Phys. 71, 242 (2001).
5. G. R. Li, G. K. Liu, and Y. X. Tong, Electrochem. Commun. 6, 441 (2004).