@article {251, title = {Soil nitrous oxide and nitric oxide emissions as indicators of the exceedance of critical loads of atmospheric nitrogen deposition in semi-natural ecosystems}, journal = {Environmental Pollution}, volume = {102}, year = {1998}, pages = {457-461}, author = {Skiba, U. and Sheppard, L.J. and Pitcairn, C.E.R. and Leith, I.D. and Crossley, A. and van Dijk, S. and Kennedy, V.J. and Fowler, D.} }