1. Purification of nickel sulfate;Stewart,1982
2. Sposob wytwarzania siarczanu niklawego o wysokiej czystosci z odpadu poelektrorafinacyjnego miedzi;Grysiewicz,1984
3. Production of high purity nickel sulfate from copper electrolyt;Shibasaki,1987
4. Sopversenstvovanije tekhnologii pererabotki rastvorov medeelektrolitnogo proizvodstva;Tschubarova;Tsvetsn. Metall.,1974
5. Havlík, T., Škrobian, M. and Kammel, R., Thermodynamic possibility of crude nickel sulfate refining, obtained from electrolytes of copper electrorefining. Trans. TU Kosice (in press).