# Hilbert's twenty-first problem

> On linear differential equations with certain properties

**Wikidata**: [Q4155615](https://www.wikidata.org/wiki/Q4155615)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Hilbert's_twenty-first_problem)  
**Source**: https://4ort.xyz/entity/hilbert-s-twenty-first-problem


## References

1. Freebase Data Dumps. 2013