1. Schneider, S.J., Roth, R.S., Waring, J.L., Solid State Reactions Involving Oxides of Trivalent
Cations, J. Res. Nat. Bur. Stand., 65A(4), 345-374 (1961), doi:10.6028/jres.065A.037
2. Foex, M., Traverse, J.P., Investigation of High-Temperature Allotropic Transformations for the
Yttrium, Erbium and Thulium Sesquioxides (in French), C. R. Seances Acad. Sci., 261, 2490-2493
(1965)
3. Spiridonov, F.M., Komissarova, L.N., The HfO2-Er2O3 System
(in Russian), Zh. Neorg. Khim., 15(3), 875-878 (1970)
4. Lopato, L.M., Shevchenko, A.V., Gerasimyuk, G.I., The HfO2-Al2O3
System (in Russian), Neorg. Mater., 12(9), 1623-1626 (1976)
5. Mizuno, M., Phase Diagrams of the System Al2O3-Ho2O3
and Al2O3-Er2O3 at High Temperatures (in Japanese),
J. Ceram. Assoc. Jap., 87(1008), 405-412 (1979), doi:10.2109/jcersj1950.87.1008_405