Use dictionaries, encyclopedias and research handbooks to help you understand the major theories, definitions and important thinkers associated with your topic. You can use background information to find the best keywords to use for searching for books and articles.
Not all information is good information. Remember to critically evaluate what you find:
A selection of books on education theory. For more, search Omni using keywords that describe your theory or theorist (e.g. constructivism, Piaget, etc.).