1. Center for Public Health-Kumanovo, 11-ti Oktomvri b.b., 1300 Kumanovo, Republic of North Macedonia
2. PUC “Vodovod i Kanalizacija”, 1300 Kumanovo, Republic of North Macedonia
3. Faculty of Medical Sciences, University Goce Delcev, Krste Misirkov bb, Štip, Republic of North Macedonia