Tipping E, Henrys PA, Maskell LC, Smart SM. Nitrogen deposition effects on plant species diversity; threshold loads. Environmental Pollution. 2013  ;179:218-223.

Maskell LC, Smart SM, Bullock JM, Thompson K, Stevens CJ. Nitrogen deposition causes widespread species loss in British Habitats. Global Change Biology. 2010  ;16: 671-679.