Google Scholar - Google Scholar is a freely accessible web search engine that indexes the full text of scholarly...
calibre - Ebook manager, viewer & converter
Scinapse - Scinapse is a free, nonprofit, Academic search engine for papers, serviced by Pluto Network.
FBReader - FBReader is an e-book reader for various platforms. Features:
Scopus - Scopus is a bibliographic database containing abstracts and citations for academic journal articles.
Google Play Books - Google Play Books lets you search, preview, and buy millions of books using Google Book Search.