# Hagen Karl Ehrenfest Katterfeld
**Wikidata**: [Q55090262](https://www.wikidata.org/wiki/Q55090262)  
**Source**: https://4ort.xyz/entity/hagen-karl-ehrenfest-katterfeld


## References

1. Integrated Authority File
2. Catalog of the German National Library
3. Baltisches biografisches Lexikon digital