There's also the e+Chess book app with some New In Chess publications, but it has a long loading time on my iPhone. Forward Chess is also my favorite. It seems to have the best interface and it has books by my two favorite publishers (Quality Chess and Chess Stars).
ForwardChess ebook reader app for iOS and Android (mini review)
Sort:
You can read the books with the FullReader app. I strongly advise it because it has an enormous 4.6 users-rating in Google Play. You can check this app here https://play.google.com/store/apps/details?id=com.fullreader
Updated rankings: