Аутори:
1. Risto Dambov, University GoceDelcev, Faculty of natural and technical science, Stip, Republic of Macedonia, Macedonia
2. Radmila Karanakova Stefanovska, Универзитет Гоце Делчев, Macedonia
3. Violeta Stefanova, University GoceDelcev, Faculty of natural and technical science, Stip, Republic of Macedonia, Macedonia
4. Igor Stojceski, University of St.Kliment Ohridski Bitola, Faculty of Economics - Prilep, Macedonia

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