The source of bibliographic data to be given preference as the source from which a bibliographic description (or portion thereof) is prepared (AACR2). For serials, the chief source is the title page or title page substitute of the first or earliest issue.

The source prescribed by AACR2 as the major source of data for use in bibilographic description. For example, the chief source of information for the title and statement of responsibility for a book is the title page.

The source of bibliographic data to be given preference as the source from which a bibliographic description (or portion thereof) is prepared. Example of the chief source are the title page of a book, the title screen of a video, or the title screen from a computer software product.