Eichelmann, H., Oja, V., Rasulov, B., Padu, E., Bichele, I., Pettai, H., Mols, T., Kasparova, I., Vapaavuori, E. and Laisk, A.  2004.  Photosynthetic parameters of birch (Betula pendula Roth) leaves growing in normal and in CO2- and O3-enriched atmospheres.  Plant, Cell and Environment 27: 479-495.

Heath, J., Ayres, E., Possell, M., Bardgett, R.D., Black, H.I.J., Grant, H., Ineson, P. and Kerstiens, G.  2005.  Rising atmospheric CO2 reduces sequestration of root-derived soil carbon.  Science 309: 1711-1713

Rey, A. and Jarvis, P.G.  1998.  Long-term photosynthetic acclimation to increased atmospheric CO2 concentration in young birch (Betula pendula) trees.  Tree Physiology 18: 441-450.

Riikonen, J., Holopainen, T., Oksanen, E. and Vapaavuori, E.  2005.  Leaf photosynthetic characteristics of silver birch during three years of exposure to elevated concentrations of CO2 and O3 in the field.  Tree Physiology 25: 621-632.