I'd probably use numbering for the references, and use the array of symbols* available for footnotes -- given that most pages shouldn't have more than a handful of footnotes, and you can restart your symbol order on each page. That's more difficult on longer-form web content, admittedly.

* See https://en.wikipedia.org/wiki/Note_(typography)#Numbering_an... for a sampling. These can be doubled if necessary -- so , ††, etc.