You can do export xls or an .xlsx files to CSV format. There are many programs, that can do this
And then make CSV IMPORT:
At the moment the following CSV format is supported: BookID | ISBN | Title | Authors | Language | Publisher | Description |
Fields are separated by a pipe character ( | )
You can import a whole list with just BookID and ISBN by leaving the other fields empty, for example: BookID | ISBN | empty | empty | empty | empty | empty |
Afterwards you can fetch the information from Amazon and publish
WARNING: do not use CSV import if there are Book Descriptions or Book Reviews present, in that case use XML instead!
If you have other questions, please ask.