Sorting only by upvotes will make some "classic" books be on top forever. You need to add some variation to keep the front page fresh. In HN the algorithm is essentially upvotes/age^2, so new post have a chance. (Actually, its upvotes/age^1.5 or 1.6 or some other magic number. You have to tweak it until the result looks nice.)

And you can add some other orders like https://news.ycombinator.com/best or https://hn.algolia.com/?query=%20&sort=byPopularity&prefix&p... if you want.

I agree with btian that it's a bad idea to link to pirated versions of the books. The copyright holders may not find the disclaimer at the bottom relevant.