Ahmed, A.S., Bhatty, M.B., Saeed, M.T. and Afridi, S.K. 2006. Effect of Excess Metal Concentration on the Extraction Potential of Di-(2-Ethylhexyl) Phosphoric Acid: dissociation constant, di-(2-ethylhexyl) phosphoric acid, copper extraction. Biological Sciences - PJSIR. 49, 2 (Jun. 2006), 309–313.