Hansjörg Dietz

Population age structure and reproductive behavior of the monocarpic perennial Heracleum mantegazzianum (Apiaceae) in its native and invaded distribution ranges.

Jan Pergl, Petr Pysek, J. Pergl, 2006, American journal of botany.

Linear relationships between aboveground biomass and plant cover in low open herbaceous vegetation

Wolfram Beyschlag, W. Beyschlag, H. Dietz, 2000 .