Interactive effects of elevated CO2 and O3 on photosynthesis and biomass production of clonal 5-year-old Norway spruce [Picea abies (L) Karst] under different nitrogen nutrition and irrigation treatments: - Lippert, ,M.,.; Häberle, ,K.-H.,.; Steiner, ,K.,.; Payer, ,H.-D.,.; and Rehfuess, ,K..E.. (Trees - Structure and Function, 1996)