Citation
Fewster, R.M., Buckland, S.T., Siriwardena, G.M., Baillie, S.R. & Wilson, J.D. 2000. Analysis of population trends for farmland birds using generalised additive models. Ecology 81: 1984. doi:10.1890/0012-9658(2000)081[1970:AOPTFF]2.0.CO;2]