Ron Rhodes did a very interesting and informative book entitled 'Reasoning from The Scriptures with the Jehovahs Witnesses'. If indeed it is possible to reason with them.
I do not have it now but I found it very helpful at the time.
Franz's books are the obvious starting point I suppose.
'Gentile Times Reconsidered' is interesting but I no longer feel that it is relevant because Jesus didn't show up in 1914 so to me the issue of when the Jewish temple was destroyed is of historical interest but little more.
Happy reading!