- Author: Gustav Krüger
- Language: German
- Year: 1904
- Author: Gustav Krüger
- Language: English
- Year: 1927
- Author: Gustav Krüger
- Language: German
- Year: 1898
- Author: Gustav Krüger
- Language: German
- Year: 1930
- Author: Gustav Krüger
- Language: German
- Year: 1898
- Author: Gustav Krüger
- Language: German
- Year: 1919