Thethird volume of the Zero no Kiseki light novel series, titled ‘Crossbell’s Longest Day’ will be released on 3/19. It is currently available on here on Amazon.co.jp for preorder.
Amazon is also showing a complete, three volume set. There is no pricing listed as of this time.
(EDIT: Of course Falcom posts the cover just after I write the article. Whoops. Updated!)