1. M. Katoh, T. Shigematsu,J. Radioanal. Nucl. Chem. Lett., /to be published/.
2. K.A. Gschneider, Jr., L. Eyring ed., Handbook on the Physics and Chemistry of Rare Earths, North-Holland Publ. Co., 1979.
3. Spec. Publ.;L.G. Sillen,1970
4. M. Katoh, Proceedings of Symposium on Solvent Extraction, 1984.
5. A.K. De, S.M. Khopkar, R.A. Chalmers, Solvent Extraction of Metals, Van Nostrand Reinhold Company, London, 1970.