How To Cite An Event
Cite an event by its canonical address, which never changes, and quote its lede.
Cite an event by its canonical URL, which never changes; quote its lede, which is written to stand alone, and name the sources it lists.
If it changes
Corrections are made on the page itself, dated, and never silently. A merged page's old address redirects to the one that survived, so an earlier citation still resolves.