Ya. V. Klyucharov, L. I. Skoblo, “Aluminium phosphates $\mathrm{Al}_2\mathrm{O}_3\cdot3\mathrm{P}_2\mathrm{O}_5$ and the
interaction of $\mathrm{Al}_4(\mathrm{P}_4\mathrm{O}_{12})_3$ with fused potassium chloride”, Dokl. Akad. Nauk SSSR, 154:3 (1964), 634–637
