1. Direct utilization of geothermal energy: a technical handbook;Anderson;Geothermal Resources Council, special report, No. 7,1979
2. Technical-economical aspects of the utilization of geothermal waters;Barbier;Geothermics,1986
3. Present status (1985) on utilizing geothermal energy in the Federal Republic of Germany;Haenel,1985
4. La filière géothermique: premier bilan;Lemale,1986
5. Direct Utilization of Geothermal Energy;Lienau,1979