I came across this publication when performing a search for articles about the archaeology of Harris.
It is a biannual online publication, http://www.shimajournal.org/ , which is produced in bound form annually.
The article ‘Defining the Archaeological Resource on the Isle of Harris’ by Colls & Hunter is in the current edition (Vol 4, No 2) which probably explains why my previous searches had failed to find it!
I would urge you to read the article in its entirety for it not only explains the present state of knowledge regarding the archaeology of Harris but also why the island has, largely speaking, been neglected.
The good news is that the survey upon which the article is focussed suggests that Harris is stuffed full of hidden treasures that may one day reveal the complex history of the Western Isles in greater detail.