[de] Handbuch Oberflächennahe Geothermie Springer Spektrum
[en] The Well-Trained Mind · A Guide to Classical Education at Home · 4th Edition W. W. Norton Company
[en] 60-Second Brain Teasers Pencil-Free Puzzles Fair Winds Press
[de] Handbuch Oberflächennahe Geothermie Springer Spektrum
[en] The Well-Trained Mind · A Guide to Classical Education at Home · 4th Edition W. W. Norton Company
[en] 60-Second Brain Teasers Pencil-Free Puzzles Fair Winds Press