Bak, J., Bastrup-Birk, A. (red.), Clark, D. R. (red.) & Geernaert, G. (red.) (1997).
Modelling of Effects (CALLUNA). I A. Bastrup-Birk, D. R. Clark & G. Geernaert (red.),
The Roskilde Project: Assessment of the Present State of International Environmental Observations, Research and Technology, and Identification of Future Demands (s. 88-89). National Environmental Research Institute.