1. Wyckoff R.W.G.: Crystal Structures, vol. 3. New York: John Wiley & Sons 1965.
2. Bleaney B.: Handbook on the Physics and Chemistry of Rare Earths (Gschneidner K.A. Jr., Eyring L., eds.), vol. 11, pp. 323–407. Amsterdam: North-Holland 1988.
3. Bleaney B., Leask M.J.M. in: NMR and More (Goldman M., Parneuf M., eds.), pp. 73–80. Paris: Les Editions de Physique 1994.
4. Ranon U.: Phys. Lett. A28, 228 (1968)
5. Rosenthal J.: Phys. Rev.164, 164 (1967)