# Essential spectrum

> Aspect of mathematical spectrum theory

**Wikidata**: [Q917390](https://www.wikidata.org/wiki/Q917390)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Essential_spectrum)  
**Source**: https://4ort.xyz/entity/essential-spectrum


## References

1. Freebase Data Dumps. 2013
2. [OpenAlex](https://docs.openalex.org/download-snapshot/snapshot-data-format)