Has been a request for the key via PM. I have added two appendices: Mastronarde's corrections to both the first edition of the textbook (all editions), and changes to the answer key (all editions).https://www.sendspace.com/file/57fhf1
My scan, cropped and everything. Looks like all diacritical marks are legible.
[Although under copyright, this book will not be put in print again. used copies of this key start at over 50 on amazon, and it seems a shame. If this material should not be posted on this site, I can delete the link.]