According to the story, each book has:
* 410 pages
* 40 lines per page
* 80 characters per line
* Not included: The characters on the front cover, maybe 15 on average?
There are 25 symbols.
So there are 25^(410*40*80) possible books, which comes out to ~10^1834097 books. Sufficed to say, the library could hold numerous universes.