Google Scholar

 

Google Scholar provides a simple way to broadly search for scholarly literature. From one place, you can search across many disciplines and sources: articles, theses, books, abstracts and court opinions, from academic publishers, professional societies, online repositories, universities and other web sites. Google Scholar helps you find relevant work across the world of scholarly research. Released in beta in November 2004, the Google Scholar index includes most peer-reviewed online journals of Europe and America's largest scholarly publishers, plus scholarly books and other non-peer reviewed journals" (Springer, 2016).

Search for PDF files about any title or subject with the following query: filetype:pdf  

Features of Google Scholar

Search all scholarly literature from one convenient place

Explore related works, citations, authors, and publications

Locate the complete document through your library or on the web

Keep up with recent developments in any area of research

Check who's citing your publications, create a public author profile.

Contains About 6,650,000 items as PDF.