Why you would want to ask about a Perl book in a Microsoft Access forum is beyond me, however...
As I understand it, you can find the answer to your question here: http://www.wrox.com/dynamic/books/download.aspx
and then read follow the links to the FAQs.
Apparently, the brand "Wrox" is now owned by Wiley, and some of Wrox's books are now likewise owned by Wiley. Other books formerly owned by Wrox are now owned by Apress.
Graham R Seach
Microsoft Access MVP