- Author: Carl-Heinrich Bösling, Ursula Führer, Claudia Junk, Thomas F. Schneider
- Language: German
- Year: 2017
- Author: Claudia Junk, Thomas F. Schneider
- Language: German
- Year: 2021
- Author: Georg Simmel
- Language: German
- Year: 1911
- Author: Valeria Sgambati
- Language: Italian
- Year: 2023
- Author: George Nyamndi
- Language: English
- Year: 1983
- Author: Hans Jørgensen
- Language: English
- Year: 1941