WordPress.org

Known issues

1. There are ISBNs that ended with 'x' not a number. In that cases, you should take care of the case sensitivity of the 'x', because some book store use the lower case 'x' for their image file name, and some the upper case. So, try one, and if it fail try another.
2. There is no validation check on plugin configuration page. So you can submit with empty country code and empty URI. It makes default URI for other country code null.