E-text of books, many are full-text with no restrictions. Excellent source for books published after conflicts prior to 1950. Largest collection is pre-1923. Search by topic or keyword to locate books. Also includes government reports.
On the advanced search page, limit your search to the years of your project to find primary resources. Books that are not full-text can be requested from the Public Library using Interlibrary Loan
An excellent search engine. This will help you find books, dissertations, and other materials. It will provide a list of which libraries have the article you are looking for. Sometimes it will also include a link to the item.