WordNet (r) 3.0 (2006):

reference book
    n 1: a book to which you can refer for authoritative facts; "he
         contributed articles to the basic reference work on that
         topic" [syn: reference book, reference, reference
         work, book of facts]

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "reference book":
   Baedeker, Yellow Pages, atlas, bibliography, business directory,
   calendar, casebook, catalog, catalogue raisonne, checklist,
   city directory, classified catalog, classified directory,
   concordance, cyclopedia, diatesseron, dictionary catalog,
   directory, encyclopedia, finding list, gazetteer, guidebook,
   handbook, handlist, harmony, index, itinerary, phone book,
   polyglot, record book, road map, roadbook, source book, studbook,
   telephone book, telephone directory, work of reference