Given the Internet, a hard copy set of an encyclopedia is no longer needed, but there are still several other helpful print books I may reach for when writing. Online definitions from various sources aside, the hardcover Gage Canadian Dictionary and The Concise Oxford Dictionary provide whatever basic definitions and reminders of spellings and pronunciations.
Nothing is worse than referencing a specific you know by sight but can’t name. Two useful visual dictionaries are Merriam-Webster’s Compact Visual Dictionary and What’s What: A Visual Glossary. I also still own a 1962 copy of the classic red and black paperbound I used in high school–The New American Roget’s College Thesaurus, the handiest-ever, easy-to-use thesaurus for looking up synonyms or more exact word choice. It is very simple and quite concise to use, quickly opening up vistas of language possibilities, meanings, and nuances. Definitely a desert island classic.
Two helpful softcover ‘bathroom’ or ‘waiting room’ language reference books are Word Nerd and Phraseology by Barbara Ann Kipfer. In order to use language fluently, it helps to know, understand, and appreciate the origins and meanings of common or famous expressions. Other titles such as 1000 English Idioms Explained or The Oxford Dictionary of Allusions cover more well-known phrases and basic allusions.
Of late, I have received many prompts and ideas for writing from books of quotations. Some of the better wide-ranging and comprehensive ones I have used include: The Penguin Dictionary of Quotations, Pepper’s 20th Century Quotations, Bloomsbury’s Thematic Dictionary of Quotations, The New Beacon Book of Quotations by Women, and Partnow’s The New Quotable Woman.
Handbooks of various kinds might be referred to basic grammar questions. Beyond that, for more enthusiastic word fans, I would highly recommend the fascinating labor of love by the Crystal brothers Shakespeare’s Words: A Glossary & Language Companion. Shakespeare, of course, was the ultimate poet who changed our language more than any other person in history. If ever I was to be asked for an example of the widest range of possibilities of the English language (beyond a dictionary or thesaurus), that would be the ultimate book. Great birthday or Christmas gift, by the way!