- https://en.wikipedia.org/wiki/Markdown
- https://en.wikipedia.org/wiki/Markup_language
- https://en.wikipedia.org/wiki/Lightweight_markup_language — includes various tables
- http://daringfireball.net/projects/markdown/syntax – where it all began
- http://www.markdowntutorial.com
- http://www.markdowntutorial.com/conclusion/
- https://help.github.com/articles/basic-writing-and-formatting-syntax/
- https://github.github.com/gfm/ – GitHub Flavored Markdown spec
- https://gitlab.com/help/user/markdown – GitLab Flavored Markdown spec (a customer GitLab installation provides (resp. seems to provide) a version with a TOC)
- https://jira.atlassian.com/secure/WikiRendererHelpAction.jspa – Jira and its markup language
- https://en.wikipedia.org/wiki/Creole_(markup)
- http://overapi.com/org-mode – Emacs org-mode and its markup language
Emacs and Markdown: