1. M. V. Mokhosoev, Chemistry of Rare Elements, Part 1: Molybdates and Tungstates (Donetsk, 1971) [in Russian].
2. F. M. Perel’man and A. Ya. Zvorykin, Molybdenum and Tungsten (Nauka, Moscow, 1968) [in Russian].
3. G. K. Shurdumov, B. K. Shurdumov, T. N. Khokonova, et al., in Physics and Chemistry of Promising Materials, Collected Works (Izd. KBGU, Nalchik, 1998), p. 45 [in Russian].
4. A. M. Gurvich, Introduction to the Physical Chemistry of Crystal Prosphors (Vysshaya Shkola, Moscow, 1972) [in Russian].
5. Chemistry of Molybdenym(VI) and Tungsten(VI) Compounds (Nauka, Novosibirsk, 1979) [in Russian].