Lewis, J.D., Wang, X.Z., Griffin, K.L. and Tissue, D.T.  2002.  Effects of age and ontogeny on photosynthetic responses of a determinate annual plant to elevated CO2 concentrations.  Plant, Cell and Environment 25: 359-368.

Loreto, F., Harley, P.C., Di Marco, G. and Sharkey, T.D.  1992.  Estimation of mesophyll conductance to CO2 flux by three different methods.  Plant Physiology 98: 1437-1443.