J.N. Galloway, et al. (Sep 2004). „Nitrogen cycles: past, present, and future”. Biogeochemistry70 (2): 153-226. DOI:10.1007/s10533-004-0370-0.
E.A. Davidson & W. Kingerlee (1997). „A global inventory of nitric oxide emissions from soils”. Nutrient Cycling in Agroecosystems48: 37-50. DOI:10.1023/A:1009738715891.