# Approximability of HNN-extensions with central associated subgroups by a root class of groups

> Research article (Mathematical Notes, 2015) · cited 14× · AI/ML

**Wikidata**: [openalex:W2226267574](https://www.wikidata.org/wiki/openalex:W2226267574)  
**Source**: https://4ort.xyz/entity/approximability-of-hnn-extensions-with-central-associated-subgroups-by-a-root-class-of-groups