A reference book is a specialized resource (encyclopedia, dictionary, handbook, atlas, guidebook, etc.) that will help you narrow your topic and identify additional books and articles related to your topic.
The library owns a number of sources in our Reference Collection (1st Floor) about Shakespeare. This following link will take you to a list titles in our Reference Collection: Reference Books about Shakespeare. You can also search in the library catalog (linked below) for Shakespeare as a Subject and then refine your search to the Reference Collection.
The library subscribes to a number of Reference Databases and individual Reference Books that may contain relevant and related information to your research on Shakespeare.