2Theo Lehner. Integrated recycling of non-ferrous metals at Boliden Ltd. Ronnskir Smelter. EEE International Symposium on Electronics & the Enivronment, 1998:42 - 47
3Dunning BWJr. Precious Matals Recovery from Electronic scrap and solder Used in Electroncis Manufacture. Precious Metals Recovery Low Grade Resource , IC 9059(Washington,DC: USBureau of Mines, 1986) ,44 - 56
4G loe K, Muehl P and Konthe M. Recovery of Precious Metals from Electronic Scrap, in Paritcular from Waste Products of the Thick-layer Technique. Hydrometallurgy,1990, (25): 99 - 110