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Bogna Zawieja
Poznań University of Life Sciences, Faculty of Agronomy and Bioengineering, Department of Mathematical and Statistical Methods,Wojska Polskiego 28, 60-637 Poznań, Poland, phone: 48 61 8487153
Katarzyna Kaźmierczak
Poznań University of Life Sciences, Faculty of Forestry, Department of Forest Management, Wojska Polskiego 28, 60-637 Poznań, Poland