A reference work is a type of publication that provides information on a particular subject. An ATLAS (5 letters) is a collection of maps and diagrams, often including facts and figures about the places depicted. A TOME (4 letters) is a large book, usually one that is scholarly or technical in nature. An encyclopaedia (13 letters) is a comprehensive reference work containing information on all branches of knowledge. A commonplace book (15 letters) is a collection of quotations, notes, and other materials compiled by an individual for personal use. All of these are examples of reference works.