1. University of Forestry - Sofia, Faculty of Forest Industry, Department of Mechanical Technology of Wood, Sofia, Bulgaria
2. University of Forestry - Sofia, Faculty of Ecology and Landscape Architecture, Department of Plant Pathology and Chemistry, Sofia, Bulgaria
3. University of Forestry, Sofia, Bulgaria
4. Department of Wood Industry, Faculty of Applied Sciences, Universiti Teknologi MARA Pahang Branch Campus Jengka, Pahang, Malaysia