Unfortunately, this issue of MYTHLORE falls among those I still have inaccessibly boxed away. But if this person is looking for a copy, he needs to be warned that this issue is NOT #15 but part of VOLUME 15. The issue he's looking for would be somewhere around #56.
I do have a copy of the dissertation, though in rather battered condition, and so could provide a copy of specific pages or passages if he can't find one for himself; I believe Marquette and probably Wheaton have copies as well. And since the dissertation was for a degree granted at the University of Southern California, there shd be a copy on file there as well.
At least one important excerpt from this dissertation has been published as an essay: "Gollum's Character Transformation in The Hobbit", which lays out the changes between the first and second editions of the Gollum-scene in parallel columns. It appears in Lobdell's A TOLKIEN COMPASS (both the original 1975 edition and the truncated 2003 re-issue).
--John R.