Author: zskoda Format: MarkdownItexAdded a bit, including the original reference by G. B.
<a href="https://ncatlab.org/nlab/revision/diff/Birkhoff%27s+HSP+theorem/7">diff</a>, <a href="https://ncatlab.org/nlab/revision/Birkhoff%27s+HSP+theorem/7">v7</a>, <a href="https://ncatlab.org/nlab/show/Birkhoff%27s+HSP+theorem">current</a>
Added a bit, including the original reference by G. B.