1. G. M. Ritcey and A. W. Ashbrook , “ Solvent Extraction. Principles and Applications to Process Metallurgy, ” Part II, Elsevier, Amsterdam Oxford s :New York, 1979 .
2. Solvent extraction with di(2-ethylhexyl)phosphoric acid; A correlation between selectivity and the structure of the complex
3. Chuel Biing-yi , Yu Jing-fen and Zhang Liang-ping ,Proc. Intern. Solv. Extr. Conf. ISEC 83, Denver,(Colorado)August 26-September 2, 1983 , American Institute of Chemical Engineers page 193 .