I was just noticing that a book that came out this year was listed with a short ISBN. Why would that happen?  Seems like any book from an established publisher should have an ISBN these days.

One possibility--If a book is listed in the system as one type of binding (hardcover for example) but the paperback has the same ISBN then it would need to be entered in the system as being without an ISBN.

Or it's a book club edition. I have a few book club editions that don't come up at all, come up as the wrong binding or a completely different book. They're all 2009/2010 releases. 

Also sometimes people will create a listing like that when they don't know the ISBN of an upcoming release.  Which they shouldn't do because those ISBN are only supposed to be used for that one copy. But people get impatient and want to start the WL. 

Most common is the binding - both HC and paperback are issued under the same ISBN and only one can use the listing here first one in gets the ISBN and all others need to be posted as a book without an ISBN.

Another that I have seen more frequently in the forums these days is that the ISBN is being recycled (even though it shouldn't be) so the original book released ages ago is already in the system and the new release using the same ISBN needs to be posted as a book without an ISBN.

Some books by very small publishers also don't use ISBNs.  Our own PBS Cookbook does not have an ISBN, because it was not financially feasible to get one :-)

Cheers,

Catt

My first thought went to book clubs.  The hardback versions of paperback books.  The trade sized paperback versions of hardbacks through paperback book club.

But there are a couple of publishers that use one ISBN number for all versions of one book.  For the audio, the large print, and the hardback.