What are some alternatives?
When comparing FBReader and Google Play Books, you can also consider the following products
calibre - Ebook manager, viewer & converter
Amazon Kindle - Amazon Kindle software lets you read ebooks on your Kindle, iPhone, iPad, PC, Mac, BlackBerry, and...
Cool Reader - Fast and small cross-platform eBook reader for desktops and handheld devices
Sumatra PDF - Sumatra PDF is a slim PDF/DjVu/EPUB/XPS/CHM/CBR/CBZ/MOBI viewer for Windows.
Project Gutenberg - Project Gutenberg offers free ebooks to download.
Document Viewer - Document Viewer is a highly customizable document viewer for Android. - SufficientlySecure/document-viewer