# aleph null

> cardinal of the set of all natural numbers, and more generally of any well-ordered and countable infinite set

**Wikidata**: [Q1445491](https://www.wikidata.org/wiki/Q1445491)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Aleph-null)  
**Source**: https://4ort.xyz/entity/aleph-null


## References

1. [Source](https://jeff560.tripod.com/set.html)
2. [Ordnungen, Verbände und Relationen mit Anwendungen. Springer Vieweg Verlag. 2012](https://books.google.de/books?id=oO-BNnhNYkMC&pg=PA137)