van der Westhuizen, D., G. Lachmann, and H. Krieg. “The Possibility of Membrane-Based Solvent-Extraction (MBSX) As a Separation Method for Zr and Hf in Aqueous Solutions”. Suid-Afrikaans Tydskrif Vir Natuurwetenskap En Tegnologie / <i>South African Journal of Science and Technology</I&gt;, Vol. 33, no. 1, June 2014, p. 1 bladsy, doi:10.4102/satnt.v33i1.938.