* If it's only for authors, the form should clearly state that at the beginning. Not just loosely imply it by using the phrase "your textbook," which could easily mean one that the reader owns or uses.

* There should be a link to a form where regular visitors (non-authors) can submit books. It would be more appropriate for their staff to follow-up with authors anyway at that point, once given the leads.

Based on your scenario and if this was successful, wouldn't the incentive/money for authors to write new textbooks be removed?