1. Department of Forest Utilisation, Faculty of Forestry, Poznań University of Life Sciences, Poznań, Poland
2. Department of Forest Engineering, Forest Management Planning and Terrestrial Measurements, Faculty of Silviculture and Forest Engineering, Transilvania University of Brasov, Brasov, Romania
3. Department of Forest Engineering, Faculty of Forestry, University of Zagreb, Zagreb,Croatia
4. Latvian State Forest Research Institute Silava, Salaspils, Latvia