GLN 15-16 contains entries taken from bibliographies, from library catalogues (printed or online), and from other sources. Websites consulted are not listed here because of their instability. On the other hand, the bibliographies and catalogues consulted are listed, and are classified in five groups

• Bibliographies of authors or of literary works (sorted by author's name)
• Library catalogues (sorted by location of libraries)
• Bibliographies of publishers and printers (sorted by publisher's name)
• Bibliographies of literary genres (sorted by genre)
• Bibliographies by place or region of edition (sorted by place name)