1. Bludssus, W., Eckert, J., 1993. Process for the recovery and separation of tantalum and niobium. U.S. Patent 5209910.
2. Cardon, P.B., 1962. Process for recovering niobium and tantalum from ores and ores concentrates containing same. U.S. Patent 3058825.
3. Hydrometallurgical processing of Ta/Nb compounds. Present state of the art;Eckert,1995
4. Extraction of niobium and tantalum from nitrate and sulfate media by using MIBK;El-Hussaini;Mineral Processing and Extractive Metallurgy Review,2001
5. Sulfuric acid leaching of Kab Amiri niobium–tantalum bearing minerals, Central Eastern Desert, Egypt;El-Hussaini;Hydrometallurgy,2002