1. Hung-Shui-Chieh and Jen-Hung-Tieh, RZhKhim., 8G65 (1966);
2. A. A. Tikhonova and N. I. Timofeeva, Zh. Analiticheskoi Khim.,21 (1966);
3. A. G. Petrenko and L. A. Kuznetsova, in: Chemical Analysis of Nonferrous and Rare Metals [in Russian], Izd. SO AN SSSR, Novosibirsk (1964).
4. S. F. Makarova, P. A. Andreev, and G. I. Smirnova, Steklo i Keramika, No. 5 (1972).