NORMAL GEOTHERMY-DESIGN PRINCIPLES OF GEOTHERMAL SYSTEMS AND APPLICATIONS - Vrachopoulos, Michalis; Koukou, Maria; Karytsas, Konstantinos; Βραχόπουλος, Μιχάλης; Κούκου, Μαρία; Καρύτσας, Κωνσταντίνος (2015)