WordNet sense 1 (a publication (or a passage from a publication) that is referred to):

source

WordNet sense 2 (an indicator that orients you generally):

reference point, point of reference

WordNet sense 3 (a remark that calls attention to something or someone):

mention

WordNet sense 4 (a short note recognizing a source of information or of a quoted passage):

acknowledgment, citation, cite, credit, quotation

WordNet sense 5 (a formal recommendation by a former employer to a potential future employer describing the person's qualifications and dependability):

character, character reference

WordNet sense 6 (a book to which you can refer for authoritative facts):

reference book, book of facts, reference work

WordNet sense 7 (the most direct or specific meaning of a word or expression; the class of objects that an expression refers to):

denotation, extension

WordNet sense 8 (the act of referring or consulting):

consultation