1. International Energy Agency (IEA) , Global demand for pure hydrogen , 1975–2018 , https://www.iea.org/data-and-statistics/charts/global-demand-for-pure-hydrogen-1975-2018
2. Ammonia as a Renewable Energy Transportation Media
3. Techno-economic assessment of commercial ammonia synthesis methods in coastal areas of Germany
4. US Geological Survey (USGS), Nitrogen Statistics and Information, https://www.usgs.gov/centers/nmic/nitrogen-statistics-and-information
5. Food and Agriculture Organization (FAO) , World fertilizer trends and outlook to 2022 , Rome, Italy , 2019