Books are available in both print and electronic formats. They:
You can find a growing number of ebooks in the Union Presbyterian Libraries Collection. This link takes you to the catalog page. Change the dropdown menu in Collection to Search (located under where you would enter a book title) from "Entire Collection" to "E-Books."
In addition to the e-books to which the Union Presbyterian Libraries subscribe, there are millions of free ebooks available on the Internet. Some of the reputable sites that you can consult are located below. These tend not to have many books in religion or theology but they do have ebooks in many other areas that may be useful to a certain type of research project.