Arp, W.J., Van Mierlo, J.E.M., Berendse, F. and Snijders, W.  1998.  Interactions between elevated CO2 concentration, nitrogen and water: effects on growth and water use of six perennial plant species.  Plant, Cell and Environment 21: 1-11.

Hunt, R., Hand, D.W., Hannah, M.A. and Neal, A.M.  1991.  Response to CO2 enrichment in 27 herbaceous species.  Functional Ecology 5: 410-421.

Hunt, R., Hand, D.W., Hannah, M.A. and Neal, A.M.  1995.  Temporal and nutritional influences on the response to elevated CO2 in selected British grasses.  Annals of Botany 75: 207-216.