1. Sulfuric acid leaching of Kab Amiri niobium–tantalum bearing minerals, Central Eastern Desert, Egypt;El-Hussaini;Hydrometallurgy,2002
2. Production of high purity tantalum oxide by solvent extraction;Feather,2001
3. Gupta, C.K., Suri, A.K., 1993. Studies in niobium extraction. Proc. Klaus Schulze Symp. Process. Appl. High Purity Refract. Met. Alloys (Published 1994), pp. 31–50. CA 121:138089 (1994).
4. Extractive Metallurgy of Niobium;Gupta,1994
5. A Textbook of Hydrometallurgy;Habashi,1993