Knowing how to quote a bibliography correctly is essential for the presentation of academic papers. Our goal is to provide some guidelines for the preparation and presentation of citations and references that are useful for the preparation and presentation of study or research works.

What is a citation?

An indication of a relevant reference in the text

What is a bibliographic reference?

The data described in a document or part of it, in order to identify and locate it

What aspects must be considered to make citations or references?

  • The bibliographic elements that must be present (author, title, publication date, etc.) according to the type of reference material.
  • The sequence must follow these items.
  • The score should be used to separate one element from the next.

Style rules to make quotations and references

Both citations and references should be developed in accordance with a rule or standard, among which ISO 690

The International Organization for Standardization (ISO) developed the ISO 690: 2010 Information and documentation - Guidelines for bibliographic references and citations to information resources being translated into Spanish, UNE-ISO 690 Information and documentation. Guidelines for writing references and citation of information resources in May 2013 by the AENOR. This standard is a general framework for the presentation of citations and bibliographies. ISO 690 is not a style, but the guidelines for the minimum data to indicate when mentioning.


If ISO 690 is the framework that gives the minimum guidelines for bibliographic references, there are multiple entities that develop their own style manuals, covering the entire process of preparation and editing a manuscript, both in content and in presentation. Furthermore they define the specific aspects of quotations and references, such as punctuation, spelling, typography, abbreviations, etc.

The main styles are:

  • APA (AMERICAN PSYCHOLOGICAL ASSOCIATION). It is of reference its Publication Manual of the APA, widely used in the social sciences.
  • MLA (MODERN LANGUAGE ASSOCIATION). It is widely used in literature, arts and humanities under the rules of MLA Handbook for Writers of Research.
  • VANCOUVER RULES. These rules are an agreement between editors of leading international biomedical journals
  • HARVARD STYLE. It is a style dating, also called author-year.Es un estilo de citas, también llamado de autor-año.
  • IEEE (INSTITUTE OF ELECTRICAL AND ELECTRONICAL ENGINEERS). For use in computers and electronics. Sources are indicated by a number and the reference list is sorted numerically in order of appearance in the text.
  • UNIVERSITY OF CHICAGO. The Chicago Manual of Style offers two ways to cite the sources consulted in the development of an academic work. The first is with footnotes page and, if deemed necessary, a bibliography at the end of the document; is the preferred style in the arts, history and literature. The second, however, presents the complete information about the works consulted in a list of literature, usually called "References" or "Sources consulted" at the end of the document; the mention of the works throughout the text is the author-year (in parentheses the author's surname and the year of publication of the work, and the page number if necessary), and is the recommended style for science natural and social sciences

The following section (General guidelines for making references) presents an adapted summary ISO 690: 2010 and UNE-ISO equivalent 690-2013. This rule explains the criteria to be followed for the preparation of bibliographic references. In it the order of the elements of the bibliographic references and conventions for the transcription and presentation of information is established. However, punctuation and typographic style are not prescriptive, so here is shown to be understood as a simple recommendation.