This is actually a pretty good list:http://artofmanliness.com/2008/05/14/100-must-read-books-the-essential-mans-library/
Serenity if you get assigned old books, there's some chance some of them are available here.. http://www.gutenberg.org/A digital version could be useful when you need to backtrack to some section using the find (ctrl+f) function. Idealy though, when you write these kinds of essays, you know the material by heart, from head to toe.
Ayn Rand boring, NOT! She was wrong, but not boring.