1. G. Kirchhoff, R. Bunsen, Annalen der Physik und. Chemie 109, 275 (1860)
2. https://www.esrl.noaa.gov/gmd/ccgg/trends-ch4/
3. http://www.physicalgeography.net/fundamentals/7h.html
4. https://en.wikipedia.org/wiki/Atmospheric-methane
5. https://www.nationalgeographic.com/environment/article/methane