LeCain, D.R. and Morgan, J.A. 1998. Growth, gas exchange, leaf nitrogen and carbohydrate concentrations in NAD-ME and NADP-ME C4 grasses grown in elevated CO2. Physiologia Plantarum 102: 297-306.

Lee, T.D., Barrott, S.H. and Reich, P.B. 2011. Photosynthetic responses of 13 grassland species across 11 years of free-air CO2 enrichment is modest, consistent and independent of N supply. Global Change Biology 17: 2893-2904.

Stamenkovic, J. and Gustin, M.S. 2009. Nonstomatal versus stomatal uptake of atmospheric mercury. Environmental Science and Technology 43: 1367-1372.