1. Miara , M. Günther , D. Kramer , T. Oltersdorf , T Wapler , J. Wärmepumpeneffizienz. Final Report 0327401A of Federal Ministry for Economics, 2011.
2. Karagiorgas , M. Mendrinos , D. Karytsas , C. Solar and geothermal heating and cooling of the European Centre for Public Law building in Greece, Renewable Energy, Vol. 29 (2004), No. 4, pp. 461-470.
3. IEA, 2002.
4. Rafferty , K. Direct-use temperature requirements - A few rules of thumb. Geo heat center quarterly bulletin, Vol. 25 (2004), No. 2.
5. Zeng , H. Diao , N. Fang , Z. Heat transfer analysis of boreholes in vertical ground heat exchangers, International Journal of Heat and Mass Transfer 46 (2003), pp. 4467-4481.