These guide books can help you improve your writing skills or brush up on the style conventions of academic writing.
The Joy of Syntax by 
They Say / I Say by 
These all purpose books define literary terms, identify fictional characters and places, and give biographical information on authors. They are valuable as sources of quick information.
The Oxford English Dictionary is the accepted authority on the evolution of the English language over the last millennium. It is a guide to the meaning, history, and pronunciation of over half a million words, both present and past. It traces the usage of words through millions of quotations from a wide range of international English language sources, from classic literature and specialized periodicals, to film scripts and cook books. Hundreds of new entries are added annually.
Search by keyword or topic for book chapters from Cambridge's collection of introductory texts. Topics include literature, poetry, theatre, philosophy, religion, history, and culture. Chapters include synopses and further reading.
The Oxford Companion to English Literature by 