1. reportFourth “energy transition” monitoring report, https://www.bmwi.de/BMWi/Redaktion/PDF/V/vierter-monitoring-bericht-energie-der-zukunft-englische-kurzfassung,property=pdf,bereich=bmwi2012,sprache=de,rwb=true.pdf.
2. Information portal renewable energy, http://www.erneuerbare-energien.de/EE/Navigation/DE/Service/Erneuerbare_Energien_in_Zahlen/Zeitreihen/zeitreihen.htm.
3. Towards a low carbon energy future–renewable energy cooperation between Germany and Norway;Gullberg;Renew. Energy,2014
4. Grid-connected intermittent renewables are the last to be stored;Swift-Hook;Renew. Energy,2010
5. The value of storage on power systems with intermittent energy sources;Swift-Hook;Renew. Energy,1994