Many libraries have copies these books in their DEWEY collections too – the same book, but ready for you to check out.  Some common reference books include (and remember, there are more):

• Almanacs. These are annual publications that contain calendars, facts, statistics, and other information. An example is the Old Farmer’s Almanac.
• Interesting Facts & Figures. These books are like dictionaries of information – things that are fun to know. An example is the Guinness World Book of Records.
• Atlases. These are collections of maps, bound into book form. They also often tell us about the maps, perhaps including information about geographic features and political boundaries, social, religious and economic data.
• Dictionaries. These contain alphabetical list of words, pronunciations, and definitions. A common example is Webster’s Dictionary. There are a variety of specialty dictionaries too, like Scholastic Rhyming Dictionary.
• Encyclopedias.  These are usually sets of books, though sometimes specialty topic-specific encyclopedias are just one book.  They contain general information about people, places, and things. 
• Thesaurus. These are books about words with the same meaning (synonyms) and books with opposite meanings (antonyms). An example is Roger’s Thesaurus.

Encyclopedias. These are books, organized alphabetically, that give general information about topics. The provide overviews to help people get started with research or learning. There are general encyclopedias (like World Book) and specialty encyclopedias like Science Encyclopedia.