# John Hajdu Heyer
**Wikidata**: [Q111498994](https://www.wikidata.org/wiki/Q111498994)  
**Source**: https://4ort.xyz/entity/john-hajdu-heyer


## References

1. Integrated Authority File
2. Virtual International Authority File
3. Czech National Authority Database
4. NUKAT
5. Prabook
6. Répertoire International des Sources Musicales
7. CONOR.SI
8. National Library of Israel Names and Subjects Authority File