Take a look at gadgets on enwp, especially citation expander

[Daniel-Mietchen]

As per
https://en.wikipedia.org/wiki/Wikipedia:Gadget
and https://en.wikipedia.org/wiki/Wikipedia:Citation_expander .

[Daniel-Mietchen]

Things are about to change in terms of the wiki editor, as per
https://www.mediawiki.org/wiki/2017_wikitext_editor .
Not clear yet what this will mean in terms of hooks for gadgets, as discussed at
https://www.mediawiki.org/wiki/Topic:Tdm3yeyomhbjloap .