Google Books

For those of you on a budget or struggling with access to sufficient textual sources for your papers, note that a significant amount of info can be found online for free via google books.

Do a google search for a key word or topic you're researching.
Once the results have been returned, select "more" from the drop down menu and then select books.

This will provide you with a search results for books that google has scanned, highlighted your searched terms in these texts and allowing you to browse for free to check for relevance.

In some cases, I've quoted directly from these electronic sources (you can find the needed info for your bibliography by scrolling to the top, where you'll find the scans of the first few pages inside the cover that will give you publisher and date).

In other cases, I've subsequently searched for copies of the text online (Amazon and others) so I can have the benefit of the full physical text to allow me to browse more thoroughly.

This approach has helped me quickly broaden my perspective and deepen my bibliography for my current term papers.
Hope you find this useful as well.