Karen, at the ISBN Agency we've discovered that this is not consistent. Amazon doesn't supply an ISBN - the publisher does. And many publishers don't bother assigning an ISBN to their mobi files, because it's not a requirement at Amazon. BN/Nook assigns a proprietary EAN if no ISBN is provided by the publisher. Best practice dictates that different formats receive unique ISBNs, but many publishers don't adhere to that.
The number soars, but not consistently.
Another interesting piece of data:
For eBooks, if they are distributed by different vendors (Amazon v.
iTunes, etc.), each VENDOR provides a different ISBN. So the exact
same thing gets more than one ISBN. Also, every different eBook
format from the same vendor is supposed to have a different ISBN:
PDF, ePub, Mobi, etc. So as we go more digital, the number of ISBNs
On 5/20/13 7:05 AM, David Weinberger
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this information from Mac Elrod and Shlomo Sanders the
frequency of ISBNs publicly bloggable? It's very interesting.
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