Bookshare Developer Blog
Bookshare provides the ability for members to view a history of their prior downloads. Members frequently access their download history to find books they have previously downloaded. Because of this, it is important that you use a user authenticated download request, if you know who the current user is, even when downloading freely-available titles.
If you application is not following this approach, please change it as soon as possible. Please let us know, if you have any questions.