020 Tags: Guidelines for Multiple ISBNs
Revised November 8, 2006

Where multiple ISBNs exist, enter as many as you find, whether on the verso or the back cover. Here are the official guidelines for entering multiple ISBNs:

Enter each ISBN in a separate 020 field. DO NOT repeat subfield $a in a single 020.
Examples, 10 digits:
020  $a0379005514
020  $a0373198167

Example, 13 digits:
020  $a9780373198160
020  $a9780533801811

If a book has ISBNs for both the hard cover and paperback editions and if the publishers are the same, enter both ISBNs in separate 020 fields. If publishers are not the same, separate bibliographic records are required, each with its appropriate ISBN in a 020 field.

In the case of one volume of a multivolume set, include both the number for the volume and the set number, if available. Enter the number for the volume first. Use separate 020 fields.

Example:
020  $a0379005514 (v.1)
020  $a0379005506 (set)

In the case of a multivolume monograph (where all volumes share the same title), enter both the set number and the individual volume numbers, if available. Enter the number for the set first. Use separate 020 fields.

Example: The World Book Dictionary, 2 vols.
020  $a0716602768 (set)
020  $a0716602792 (v.1)
020  $a0716602806 (v.2)

Note: No indicator is used for either position, so both indicator spaces are blank.