I just realized that the name of the city "Nienburg/Weser" is misspelled in geotree (http://geotree.geonames.org/6558437/): "Nienburg (Weser)". It was also misspelled in geonames itself (while the county is spelled correctly). I already changed it where I could, but it doesn't seem possible to edit the geotree entries and therefore I'm reporting this error here.
Please correct the name to "Nienburg/Weser".
Thank you.