Which GTINs are used for newspapers and magazines?

Many publishers will use the ISSN (International Standard Serial Number) for their serial publication (i.e. a magazine or newspaper) as the basis for the GTIN that they will assign to it. It is possible to convert the ISSN into a GS1 GTIN format.

See http://www.gs1.org/barcodes-epcrfid-id-keys/gs1-general-specifications for more information.