[https://www.researchgate.net/publication/224987427_Der_Erdsonden-Warmespeicher_in_Crailsheim Crailsheim]: 60 Sonden 55m tief 3 m Abstand in 30m Kreis | [https://www.researchgate.net/publication/224987427_Der_Erdsonden-Warmespeicher_in_Crailsheim Crailsheim]: 60 Sonden 55m tief 3 m Abstand in 30m Kreis |