The only book in English that I know of that discuss Ottonian art is Dodwell's 'The Pictorial Arts of the West 800-1200' [DODWELL 1993].<br>
[http://en.wikipedia.org/wiki/List_of_illuminated_manuscripts#9th_century Wikipedia] has a list of Illuminated Manuscripts.<br>
[http://commons.wikimedia.org/wiki/Category:Carolingian_manuscripts Wikimedia Commons] has a category containing images]