1. Department of Woodworking Machines, Faculty of Forest Industry, University of Forestry, Sofia, Bulgaria
2. Wood Science and Engineering, Luleå University of Technology, Skellefteå, Sweden
3. Institute for Building Materials, ETH Zürich, Zürich, Switzerland
4. Department of Woodworking, Faculty of Wood Science and Technology, Technical University in Zvolen, Zvolen, Slovakia
5. Department of Furniture Production, Faculty of Forest Industry, University of Forestry, Sofia, Bulgaria