Pitcairn CER, Leith ID, N. vanDijk, Sutton MA.
Refining and testing the Ellenberg Index biomonitoring method at the intensive sites. In: Biomonitoring methods for assessing the impacts of nitrogen pollution: refinement and testing. JNCC; 2005. p. 230.
Rennenberg H, Herschbach C.
Responses of plants to atmospheric sulphur. In: Plant response to air pollution. Plant response to air pollution. Chichester: John Wiley & Sons; 1996. pp. 285-294.