1. Wiki: World energy consumption; https://en.wikipedia.org/wiki/World_energy_consumption
2. World Energy Balances—2016 edition—excerpt—Key World Energy Trends; http://www.iea.org/publications/freepublications/publication/world-energy-balances—2016-edition—excerpt—key-world-energy-trends.html
3. Box: Own work; Data from World Energy Balances—2016 edition—excerpt—Key World Energy Trends; http://www.iea.org/publications/freepublications/publication/world-energy-balances—2016-edition—excerpt—key-world-energy-trends.html
4. Wiki: Energy conversion efficiency; https://en.wikipedia.org/wiki/Energy_conversion_efficiency
5. Wiki: Nuclear power; https://en.wikipedia.org/wiki/Nuclear_power