Oxford Dictionary of Shakespeare

The dictionary is good, although it doesn't discuss about all of the narrative features of the Bard. What is mostly included are the terms associated with all the drama productions, the famous stage actors who played a major role in the history of productions, dates and developments, quarto and folio editions terms, details about the Globe theatre, etc. This is a good edition for AS level/A level students and first year undergraduates. To dig deeper, I'd recommend Frank Kermode's 'Shakespeare's Language'.