Q:

A usage of "refer to"

This passage is a much fuller account of the coming of the Elves
  Gelmir and Arminas to Nargothrond in the year of its fall (The
  Silmarillion pp. 211-12); for their earlier encounter with Tuor in
  Dor-lómin, which is referred to here, see pp. 23-24 above.

This is some of the editor's comment from Unfinished Tales by J.R.R. Tolkien
I couldn't find relevant definition when I referred to the dictionary.
If it were which refers the readers to here, it feels make sense.
Could you explain or give me some example of this usage, please?

A:

is referred to is a passive construction, whose subject, which, has their earlier encounter... as its referent. That encounter is referred to here—that is, mentioned in the passage which he is currently discussing: 

And in the wastes of Dor-lómin I met with Tuor son of Huor, Húrin's brother ... (p. 169)

The reader is invited to consult pp. 23-24 of the current edition for a fuller account of that encounter.

