A thesaurus is a type of general reference book that enables better writing by enhancing the diversity of a writer's vocabulary. A word can be looked up to find alternative words, or synonyms, to be used instead. Dictionaries are another kind of general reference book where a word can be looked up to find various items like its definition, pronunciation, part of speech and etymology.
Encyclopedias are general reference books where many topics are listed in alphabetical order. Topics of interest can be looked up to provide an overview of the most important facts. The encyclopedia is available in print as sets, which include multiple volumes. Encyclopedias such as Britannica are also available online through a subscription.
A famous example of a general reference book on a specific topic is the annual Farmer's Almanac, which can be consulted for information relevant to agriculture and farming. An Atlas is a general reference book used to find maps of the entire globe. The textbooks assigned in survey classes, such as "Earth and Ocean Sciences" or "Intro to Psychology," are another form of general reference book.
Books of quotations are general reference books that can inspire readers either in their writing or the way they live their lives. Bartlett's Quotations has many famous quotes from famous figures. It can be fascinating to look up a popular saying in Bartlett's Quotations and find out who coined the phrase from which it originated.