1. Brundtland G et al (1987) Our common future (‘Brundtland report’). Oxford University Press, Oxford
2. Report on critical raw materials for the EU, in Report of the Ad hoc Working Group on defining critical raw materials. 2014, European Commission.
http://ec.europa.eu/growth/sectors/raw-materials/specific-interest/critical/index_en.htm
3. Hultgren H (2014) Varistor material information. Personal Communication
4. ABB (2014) High voltage surge arresters, Buyer’s Guide, ABB high voltage products surge arrestors. Ludvika, Sweden
5. Bernik S, Maček S, Bui A (2004) The characteristics of ZnO–Bi2O3-based varistor ceramics doped with Y2O3 and varying amounts of Sb2O3. J Eur Ceram Soc 24(6):1195–1198