K.M. Franken, A roast-leach process for extraction of rare earth from complex monazite- xenotime concentrates, Sep. Sci. and Tech., 30 (1995) 1941-1949.
 Karl A Gschneidner, Rare earths; the fraternal fifteen, U.S. Atomic Energy commission Division of Technical Information, (1964) 1-42.
 A. Bagherieh, Determination of Rare Earth Elements in Products of Chadormalu Iron Ore Concentrator Plant, Master Degree Thesis, Islamic Azad University, Science and Research Branch-Tehran, (2006) 17-57.
 S. Radhika, B. Nagaphani Kumar, M. Lakshmi Kantam, B. Ramachandra Reddy, solvent extraction and separation of rare earts from phosphoric acid solutions with TOPS 99, Hydrometallurgy, 110 (2011) 50-55.
 Danilo Fontana, Loris Pietrelli, Separation of middle rare earths by solvent extraction using 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as an extractant, Journal of Rare Earths, 27 (2009) 830-833.
 H. Li, F. Guo, Z. Zhang, D. Li, Z. Wang, A new hydrometallurgical process for extracting rare earths from apatite using solvent extraction with P350, J. of Alloys and Compounds, 408- 412 (2006) 995-998.
 R. Chi, X. Zhang, G. Zhu, Z.A. Zhou, W. Wu, C. Wang, F. Yu, Recovery of rare earth from bastnasite by ammonium chloride roasting with fluorine desactivation, Minerals Engineering, 17 (2004) 1037-1043.
 A. Bhattacharyya, P.K. Mohapatra, S.A. Ansari, D.R. Raut, V.K. Manchanda, Separation of trivalent actinides from lanthanides using hollow fiber supported liquid membrane containing Cyanex-301 as the carrier, Journal of Membrane Science, 312 (2008) 1-5.
 S. Inoue, Q. Zhang, M. Uto, Solvent extraction of lanthanides(III) with N-p-Phenylbenzoyl-N-phenylhydroxylamine, Solvent Extraction and Ion Exchange, 22 (2004) 121-133.
 W. Li, X. Wang, H. Zhang, S. Meng, D. Li, Solvent extraction of lanthanides and yttrium from nitrate medium with Cyanex 925 in heptane, Journal of Chemical Technology & Biotechnology, 82 (2007) 376-381.
 B.S. Shaibu, M.L.P. Reddy, A. Bhattacharyya, V.K. Manchanda, Evaluation of Cyanex 923-coated magnetic particles for the extraction and separation of lanthanides and actinides from nuclear waste streams, Journal of Magnetism and Magnetic Materials, 301 (2006) 312-318.
 K. Shimojo, Solvent extraction of lanthanides into an ionic liquid containing N, N, N0, N0-Tetrakis (2-pyridylmethyl) ethylenediamine, Chemistry Letters, 35 (2006) 484-485.
 J.I. Skorovarov, V.D. Kosynkin, S.D. Moiseev, N.N. Rura, Recovery of rare earth elements from phosphorites in the USSR, Journal of Alloys and Compounds, 180 (1992) 71-76.
 M. Krea, H. Khalaf, Liquid-liquid extraction of uranium and lanthanides from phosphoric acid using a synergitic DOPPA-TOPO mixture, Hydrometallurgy, 58 (2000) 215-225.
 N. Lounamaa, T. Mattila, V.P. Judin, H.E. Sund, Recovery of Rare Earths from Phosphorus Rock by Solvent Extraction. In: Proc. Second Int. Congress Phosphorus Compounds, Institute Mondial du Phosphate, Paris, (1980) 759-768.
 Liangshi Wang, Zhiqi Long, Xiaowei Huang, Ying Yu, Dali Cui, Guocheng Zhang, Rcovery of rare earths from wet-process phosphoric acid, Hydrometallurgy, 101 (2010) 41-47.
 S.A. Milani, E. Farahmand, B. Maraghe-Mianji, Recovery of Rare Earth Elements from Leach Liquor of Apatite Concentrate of Central Iran Using Combined Precipitation and Solvent Extraction Methods, Journal of Nuclear Science and Technology, 64 (2013) 56-66.
 A.R. Khanchi, H. Rafati, M.R. Rezvanyanzadeh, Recovery of some rare earth elements from leach liquor of the saghand uranium ore using combined precipitation and cation exchange methods, J. of Nuclear Sci. and Tech., 44 (2008) 1-8.
 V. Jedináková, P. Vaňura, J. Žilková, V. Bílek, F. Touati, Extraction of micro- and macro-concentrations of rare earth ions with the mixture of D2EHPA and TBP in n-hexane and cyclohexane, J. Radioanal. Nucl. Chem, 162 (1992) 267-276.
 N.E. El-Hefny, Y.A. El-Nadi, I.M. Ahmed, 18-Crown-6 for the selective extraction and separation of cerium(IV) from nitrate medium containing some lanthanides, International Journal of Mineral Processing, 101 (2011) 58-62.
 O.A.E.N. Desouky, Liquid-Liquid Extraction of Rare Earth Elements From Sulfuric Acid Solutions, Ph.D. thesis, University of Leeds, United Kingdom, (2006) 30-107.
 Harvinderpal Singh, R. Vijayalakshmi, S.L. Mishrs, C.K. Gupta, Studies on uranium extraction from phosphoric acid using di-nonyl, Hydrometallurgy, 59 (2001) 69-76.
 E.K. Alamdari, D. Darvishi, S.K. Sadrnezhaad, Z.M. Shabestari, A. O'hadizadeh, M. Akbari, Effect of TBP as a modifier for extraction of zinc and cadmium with a mixture of DEHPA and MEHPA, Proc. Int. Conf. Solvent Extraction Conference, S. Afr. Inst. Min & Metall., Johannesburg, (2002) 1052-1057.
 D. Haghshenas Fatmehsari, D. Darvishi, S. Etemadi, A.R. Eivazi Hollagh, E. Keshavarz Alamdari, A.A. Salardini, Interaction between TBP and D2EHPA during Zn, Cd, Mn, Cu, Co and Ni solvent extraction: A thermodynamic and empirical approach. J. Hydrometallurgy, 98 (2009) 143-147.