I'm not sure I can get proper documentation on this, I've been to this tumblr help center and this discussion on Meta SO about Markdown footnotes, I saw interesting comment from Arjan that Drupal made it possible.
How can I write Markdown footnotes in Tumblr?
I tried <sup>1</sup>
, which works on SE sites like so, but it doesn't work on Tumblr.
Best Answer
Make sure you've got Tumblr set to format your posts with Markdown here. Then, the syntax is:
As noted here.