# Willem Sybrand Unger
**Wikidata**: [Q28133124](https://www.wikidata.org/wiki/Q28133124)  
**Source**: https://4ort.xyz/entity/willem-sybrand-unger


## References

1. BnF authorities
2. general catalog of BnF
3. Virtual International Authority File
4. [Source](http://hdl.handle.net/10622/ARCH03903)
5. Biografisch Portaal
6. National Library of Israel Names and Subjects Authority File