Jackson, R.B. and Reynolds, H.L.  1996.  Nitrate and ammonium uptake for single- and mixed-species communities grown at elevated CO2.  Oecologia 105: 74-80.

Jia, Y., Tang, S., Wang, R., Ju, X., Ding, Y., Tu, S. and Smith, D.L. 2010. Effects of elevated CO2 on growth, photosynthesis, elemental composition, antioxidant level, and phytochelatin concentration in Lolium mutiflorum and Lolium perenne under Cd stress. Journal of Hazardous Materials 180: 384-394.

Phillips, D.A., Fox, T.C. and Six, J. 2006. Root exudation (net efflux of amino acids) may increase rhizodeposition under elevated CO2. Global Change Biology 12: 561-567.

Weigel, H.J., Pacholski, A., Burkart, S., Helal, M., Heinemeyer, O., Kleikamp, B., Mandershceid, R., Fruhauf, C., Hendrey, G.F., Lewin, K. and Nagy, J. 2005. Carbon turnover in a crop rotation under free air CO2 enrichment (FACE). Pedosphere 15: 728-738.