I purchased a replacement copy of
Hartung's last week from
The Book Depository in the U.K. It arrived today - in 8 days! But be prepared to pay for it, 73 pounds. Here is the
direct link to the order page.
The ISBN number: 9780521554916..Prior to this, I searched Amazon.com (8 of their resellers), Melbourne University Bookshop, Dimocks, and many, many others on-line, all out of stock.
The Book Depository was the only one which had the book. It arrived today. I had to replace a copy which was lost 7 years ago.
I admit I wasn't aware of
abebooks at the time so I can't comment on them, but try them also.
Also, look at
Biblioz you'll find lots of new and second-hand copies.
Here is a list of search results. Some stores are asking $500 for a new copy. Is it worth that much? I don't think so, at least while there are cheaper copies around.