No. ISBNs are issued by publishers, from delegated blocks, and there's no unified listing.

For books in the collections of large libraries (like the LoC) there will be a public catalogue entry with the ISBN attached, but they don't assign it.

There were also a lot of books published before ISBNs were created, and not every book has an ISBN attached even to this day.

That is all correct. Another consideration: occasionally an incompetent publisher puts the same ISBN on two unrelated editions. A bibliographer might just carefully record what's printed on the book, but many users of ISBNs won't be at all happy with that "solution".

I've seen a number of books, mostly children's books from scholastic, with different editions (different art, copyright, etc) that have the same ISBN number. I've since removed most duplicate books from my collection, but I had found a bunch when I last sorted my books; Maniac Magee is the only one I can remember by title. More annoying was the book with a CD attached to the front, that caused the finish to peel off when the CD was removed (the CD contained a non-working installer for a screensaver that, when extracted using other tools, also didn't work).

Correction; ISBNs are issued to publishers, by an issueing agency or firm (R. R. Bowker LLC in the US, now owned by ProQuest).

https://en.wikipedia.org/wiki/International_Standard_Book_Nu...

https://en.wikipedia.org/wiki/R._R._Bowker

http://www.bowker.com/products/ISBN-US.html

Also: ISBNs often change when publishers are bought, split, sold, merged etc.

On amazon you can get an ASIN so you don't have to buy an ISBN. So there's no universal book identifier.