Document identifiers

ISBN (International Standard Book Number):

A number that identifies publications on the commercial market (printed and electronic monographic publications, maps, films, videos, computer programs and slides with educational or instructional content for formal education, etc.). It uniquely identifies each publication and is internationally accepted.

Its inclusion is not compulsory.

In Spain it is issued by the ISBN Agency

The Ministry of Culture, Education and Sport publishes a publicly accessible database with information from the ISBN Agency.

It has been a 13-digit code since 2007:

For example: ISBN-13: 978-84-8181-227-5

The ISBNs issued before 2007 are 10-digit codes:

For example: ISBN-10: 84-8181-227-7


ISSN (International Standard Serial Number):

a number that identifies regular and serial publications in any format, printed and electronic (newspapers, annual publications such as reports or yearbooks, scientific or general journals, collections, websites, databases, etc.). It uniquely identifies each regular publication and is internationally accepted.

It is an 8-digit code formed by two groups of four digits, separated by a hyphen:

For example: ISSN 0317-8471



This covers the bibliographic output of a country and issues a unique number to each edition of each publication. It facilitates the collection and preservation of all types of publications, to protect the bibliographic, audio, visual, audiovisual and digital heritage of a country.

For example: Depósito Legal: M-108883-2016


DOI (Digital Object Identifier)

This is a persistent identifier for any digital object (an e-book, a chapter of an e-book, an article in a webzine, etc.). It is used for electronic publications, especially in scientific journals and books. It ensures that an electronic resource can always be accessed, regardless of its URL.

For example: DOI: 10.1021/ef900704h

For example: DOI:



a persistent identifier for a digital object on the internet, developed by the CNRI (Corporation for National Research Initiatives) through an open system.It ensures that an electronic resource can always be accessed by allocating it a permanent and stable URL, regardless of any changes in location.