Reference works, such as encyclopedias and handbooks, are a good place to search for ideas for a research topic and to begin your research. Their articles provide background information and context and may also list additional books and articles on your topic.
One way to find reference works is to browse the library's reference collection under the appropriate Library of Congress classification. The area for linguistics is "P", but there may additional sources elsewhere. Ask the reference librarian for assistance.
Subject specific dictionaries may be helpful if you run into unfamiliar terminology during your research or just need clarification about how a particular term is used within the discipline of linguistics.