Author: zskoda Format: MarkdownItexQuite a few references added, some of which are also scattered in $n$Lab, some not.
<a href="https://ncatlab.org/nlab/revision/diff/Eduardo+Dubuc/7">diff</a>, <a href="https://ncatlab.org/nlab/revision/Eduardo+Dubuc/7">v7</a>, <a href="https://ncatlab.org/nlab/show/Eduardo+Dubuc">current</a>
Quite a few references added, some of which are also scattered in Lab, some not.