1. P. P. Budnikov and M. Ya. Solomonov, Ceramics and Glass 9, 9 (1933).
2. Ind. Ceramique 449, 1–5 (1954);
3. E. Kempeke, Sprechsaal 1, 1–3 (1954.
4. H. Webb, Chemistry and Industry 23 (1945).
5. R. Niderleitner, Nonplastic Raw Materials for Ceramic Bodies [in Russian] (Ukrainian Local Ind. State Press, 1936).