Question [Q]Google books

hello am new to this
.. what it is I have a small problem
I have a Google play account ........ there for I can buy a apps/ books/ kinda anything really . I have a nexus 7 rooted . so when I buy a book from Google play store it saves them too and so on but kinda put them in a file I can not recognise and missing half the pages out

but I can read the book on line in my account