1. International Energy Agency, World energy outlook 2018, executive summary. https://webstore.iea.org/download/summary/190?fileName=English-WEO-2018-ES.pdf. (accessed 30.08.20).
2. International Energy Agency, World energy outlook 2018. https://www.iea.org/weo2018/. (accessed 30.08.20).
3. National Aeronautics and Space Administration, Global climate change, facts. https://climate.nasa.gov/evidence/. (accessed 30.08.20).
4. Ecotricity, When will fossil fuels run out? https://www.ecotricity.co.uk/our-green-energy/energy-independence/the-end-of-fossil-fuels. (accessed 30.08.20).
5. Union of Concerned Scientists, The hidden costs of fossil fuels. https://www.ucsusa.org/clean-energy/coal-and-other-fossil-fuels/hidden-cost-of-fossils. (accessed 30 August 2020).