How can I view books.civicrm.org?
If you are after civicrm documentation the address is book.civicrm.org  (ie no "s" on book). That takes you to a page which directs you to various documentation. 

(If you are looking for the user and admin guide for v 4.6 you can go directly to gitbook.civicrm.org.

Did you find that URL somewhere on the civicrm site?  If so, please let me know where it was so that it can be corrected.