> Or add text "retrieved on xxx xxx xxx" like Wikipedia
> often does.
That makes it clear what is being referenced, which is good.
Absent other provisions/ requirements, it does nothing to
guarantee that the content will be there when someone goes
looking for it years (or decades) later.
The only thing certain in this world is uncertainty, as someone has said. Putting a date-link in a URL is no guarantee either. And of course publications have been known to go out of print :)
