Sometimes research on 18th century, and earlier, topics necessitates the use of reference works, in order to clarify word meanings, to learn about a particular individual, to read just a bit about an ancillary concept, to gain a more complete understanding of a topic, to see one's project more clearly through the eyes of people at the time, or to find more sources. The British 18th-Century Studies Collection contains some general encyclopedias and dictionaries, bibliographies, subject dictionaries, handbooks, gazetteers, bio and bio-bibliographical dictionaries and registers, and bibliographies and catalogs. For example, there are subject dictionaries or handbooks in the collection on actors, agriculture, architecture, art, the Bible, botany, cattle, chemistry, church history, commerce, commercial law, engravers, gardening, geography, history, horse diseases, horsemanship, horses, hunting, naval art and science, painters, religions, sports, veterinary medicine, and zoology. The Collection has gazetteers (geographical dictionaries) and dictionaries of the United States, America, Great Britain, England, France, Latin America, and London. There are language dictionaries, for English, French, Gaelic, Algonquian, Italian, and Latin. For the English language there are also etymology, slang, and pronunciation dictionaries. The Collection has works leading to information about people-bio-bibliographies, biographical dictionaries, directories, and registers- for English poets, English literary authors, 17th-century French literary authors, Great Britain as a whole, Harvard University, London merchants, New England, and University of Oxford. Bibliographies and catalogs also existed in the 18th century, which lead the researcher on to other sources. There are bibliographies on, or catalogs of, agriculture, English literature, English poetry, British history, British local history, incunabula, Irish literature, Italian literature, Latin America, British manuscripts, New York State history, pamphlets, printing history, rare books, the Society of Friends, British and English theater, and travel.
Examples of some of the reference works in Special Collections itself are Samuel Johnson's Dictionary of the English Language... , (1755); Matthew Pilkington's Dictionary of Painters, from the Revival of the Art to the Present Period , (1805); Philip Miller's Gardeners and Florists Dictionary , (1724); and List of Members of the Society of Antiquaries of London, from Their Revival in 1717 to June 19, 1796, Arranged in Chronological and Alphabetical Order , (1798).