I don't know if it originates there, but it's certainly used there fairly extensively, and the wording "Maiden, Warrior, Mother, Crone" is used repeatedly in (and I think may be the title of) one of the "at the end of the book" songs.
(Which means that the possible tie-ins for DWI, if it ever gets written, could be very interesting... except for the fact that making any use of that, other than without Doug's knowledge, would almost require him to be more accepting of gods - and the Three in particular - by the end of it all, which we've seen he definitely isn't.)
(Which means that the possible tie-ins for DWI, if it ever gets written, could be very interesting... except for the fact that making any use of that, other than without Doug's knowledge, would almost require him to be more accepting of gods - and the Three in particular - by the end of it all, which we've seen he definitely isn't.)