As happens at least once or twice a year, it seems that ABE's listings are down by some 80% (figure just a guesstimate based on the numbers of messages from sellers who list on ABE). Even though they have the listings uploaded by their sellers, their search engines are just not finding them and therefore, you won't be finding them.
As always ABE's management will prevaricate, spin and lie about how long the outage will last and what its causes are. Basically, the problem is down to the technology genius who holds the title of Director of Technology (or some such) Jayson Minard, who's been with the company three years. That's the same time as Hannes Blum was promoted to President of Abebooks and about two weeks after I started listing there.
Considering he came to ABE after five years at Borland Software, which makes some pretty good software, you'd think he'd be able to sort the problems. Instead, according to old timers the problems have increased since his arrival on the scene.
Suggested remedy for those of you buying books, or wanting to. The easiest way to find the books you want and compare the prices of those books from the various sellers carrying it is to go to AddAll used book search. Its a highly configurable site and very user friendly. I wouldn't, and don't, bother with Bookfinder as it's slow, cumbersome, adds phoney shipping charges to the prices the sellers list except in the case of listings from ABE. Probably because ABE now owns it.
And another remedy would be to start shopping at listing services other than ABE, Amazon and Alibris. Many (most?) sellers add a percentage of additional cost to the cost of their books listed on those services due to various financial penalties the services charge the sellers that the smaller listing services don't.