Hesketh, J.D., Woolley, J.T. and Peters, D.B.  1984.  Leaf photosynthetic CO2 exchange rates in light and CO2 enriched environments.  Photosynthetica 18: 536-540.

Hirose, T., Ackerly, D.D., Traw, M.B. and Bazzaz, F.A.  1996.  Effects of CO2 elevation on canopy development in the stands of two co-occurring annuals.  Oecologia 108: 215-223.

Hirose, T., Ackerly, D.D., Traw, M.B., Ramseier, D. and Bazzaz, F.A.  1997.  CO2, elevation, canopy photosynthesis, and optimal leaf area index.  Ecology 78: 2339-2350.

Luo, Y.  1991.  Changes of Ci/Ca in association with stomatal and non-stomatal limitation to photosynthesis in water stressed Abutilon theophrasti.  Photosynthetica 25: 273-279.