TRANSPORT OF Cr3+, Cd2+, Pb2+, AND Ag+ IONS THROUGH BULK LIQUID MEMBRANE CONTAINING p-tert-BUTYLCALIX[4]ARENE â??TETRAETHYLESTER AS ION CARRIER - , Maming, Jumina, Dwi Siswanta and Hardjono Sastrohamidjojo ([Yogyakarta] : Fak. MIPA Universitas Gadjah Mada, 2007)