If you have added annotations or bookmarks to the ebooks on your Bookshelf, you can export them to a text file. (Highlighting itself cannot be exported.)
To export your notes:

If you have folders in your Bookshelf, you can export the book information to a text file.
To export your folder:

For each book in the folder, the CSV text file will contain the following information:
The CSV text file can be opened in Microsoft Excel or any spreadsheet or text editor.
Mori Hosseini Student Union
1 Aerospace Boulevard
Daytona Beach, FL 32114
Phone: 386-226-6595
Toll-Free: 800-678-9428