This guide will help you understand how to properly cite sources in ISO 690 format, the international standard for bibliographic references. Whether you're writing for European journals, international conferences, or institutions that require standardized citations, following ISO 690:2021 ensures your references are clear, consistent, and globally recognized.
Jan 4, 2026
By
Joe Pacal, MSc
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TL;DR
ISO 690 is an international standard offering three citation systems: author-date (Harvard), numeric, and running notes. The 4th edition (2021) provides flexible guidelines rather than rigid rules, covering everything from books to datasets and social media. Author names typically appear in CAPITALS, and the standard supports multiple languages. Key principle: citations must be deterministic—each citation maps uniquely to its source. Perfect for international publishing, European universities, and cross-disciplinary research.
What Is ISO 690?
ISO 690:2021 ("Information and Documentation—Guidelines for Bibliographic References and Citations to Information Resources") is an international standard published by the International Organization for Standardization. Now in its 4th edition (June 2021), it provides comprehensive guidelines for citing virtually any type of information resource.
Unlike prescriptive styles like APA or MLA, ISO 690 offers principles and guidelines that can be adapted to specific institutional or disciplinary needs while maintaining consistency and clarity.
Citation Systems
ISO 690 supports three citation systems:
Name and Date System (Harvard)
The creator's surname and publication year appear in the text:
Research confirms this finding (SMITH, 2022).
Smith (2022) confirmed this finding.
Numeric System
Numbers in the text (parentheses, brackets, or superscript) refer to sources in order of first citation:
Research confirms this finding [1].
Research confirms this finding (1).
Research confirms this finding¹.
Running Notes System
Numbers correspond to footnotes or endnotes:
Research confirms this finding.¹
¹ SMITH, John. Research methods. London: Publisher, 2022, p. 45.
General Formatting Principles
ISO 690:2021 emphasizes these core principles:
Deterministic output: Each citation must map uniquely back to its source
Consistency: Use the same format throughout a document
Completeness: Include sufficient information to identify and locate the resource
Author names: Typically SURNAME in capitals, followed by forename(s) or initials
Punctuation: Flexible, but periods typically separate major elements; commas separate minor elements
Citing Books (Monographs)
Format: SURNAME, Forename(s). Title: subtitle. Edition. Place: Publisher, Year. Extent. Series. Standard number.
Examples:
Single author:
SMITH, John. Research methodology in the social sciences. 3rd ed. Oxford: Oxford University Press, 2021. 456 p. ISBN 978-0-19-123456-7.
Two or three authors:
JONES, Sarah; BROWN, Michael; DAVIS, Emily. Introduction to data science. Cambridge: Cambridge University Press, 2022.
More than three authors:
WILLIAMS, Robert et al. Advanced statistical methods. New York: Springer, 2023.
Citing Edited Books
Format: EDITOR(S), ed(s). Title. Place: Publisher, Year.
Example:
ANDERSON, James; CLARK, Maria, eds. Handbook of environmental science. Berlin: De Gruyter, 2022.
Citing Book Chapters
Format: AUTHOR. Chapter title. In: EDITOR, ed. Book title. Place: Publisher, Year, p. X-Y.
Example:
TAYLOR, Elizabeth. The role of technology in education. In: MARTIN, Paul, ed. Educational innovation. London: Routledge, 2021, p. 45-78.
Citing Journal Articles
Format: AUTHOR. Article title. Journal title, Year, vol. X, no. X, p. X-Y. ISSN/DOI.
Examples:
Print article:
JOHNSON, Mark. Climate change impacts on agriculture. Nature Climate Change, 2022, vol. 12, no. 3, p. 234-241. ISSN 1758-678X.
Online article with DOI:
CHEN, Wei. Machine learning in medical diagnostics. The Lancet Digital Health [online], 2023, vol. 5, no. 4, p. e201-e210. DOI 10.1016/S2589-7500(23)00045-7.
Article without page numbers (e-locator):
KUMAR, Priya. Sustainable urban development. Sustainability [online], 2023, vol. 15, no. 8, e12345. DOI 10.3390/su15081234.
Citing Websites and Online Resources
Format: AUTHOR or ORGANIZATION. Title [online]. Date. [viewed Date]. Available from: URL.
Examples:
Website:
WORLD HEALTH ORGANIZATION. Global health statistics [online]. 2023. [viewed 2024-01-15]. Available from: https://www.who.int/data.
Web page:
EUROPEAN COMMISSION. Climate action policies [online]. Brussels, 2023. [viewed 2024-01-10]. Available from: https://ec.europa.eu/clima/policies.
Citing Dissertations and Theses
Format: AUTHOR. Title. Type. Institution, Year.
Examples:
MUELLER, Anna. Renewable energy adoption in developing economies. Doctoral thesis. University of Cambridge, 2022.
GARCIA, Carlos. Social media and political engagement. Master's thesis. London School of Economics, 2021.
Citing Conference Papers
Format: AUTHOR. Paper title. In: Conference name, Date, Location. Place: Publisher, Year, p. X-Y.
Example:
LEE, David. Artificial intelligence in healthcare. In: IEEE International Conference on Medical Informatics, 15-17 June 2022, Singapore. New York: IEEE, 2022, p. 123-130.
Citing Datasets
Format: CREATOR. Dataset title [dataset]. Version. Publisher, Year. Identifier.
Example:
EUROPEAN SPACE AGENCY. Global forest cover dataset 2020 [dataset]. Version 2.0. ESA, 2021. DOI 10.5281/zenodo.1234567.
Citing Software and Applications
Format: CREATOR. Software name. Version. Place: Publisher, Year.
Example:
R CORE TEAM. R: A language and environment for statistical computing. Version 4.3.0. Vienna: R Foundation for Statistical Computing, 2023.
Citing Social Media
Format: AUTHOR. Post content [truncated if needed]. Platform, Date. [viewed Date]. Available from: URL.
Examples:
UNESCO. Education transforms lives. Every child deserves quality learning... Twitter, 24 Sept. 2023. [viewed 2024-01-15]. Available from: https://twitter.com/UNESCO/status/123456789.
Citing Audio-Visual Materials
Format: CREATOR. Title [medium]. Place: Publisher/Producer, Year.
Examples:
Film:
NOLAN, Christopher, dir. Oppenheimer [film]. Los Angeles: Universal Pictures, 2023.
Podcast:
GLADWELL, Malcolm. The satire paradox. Revisionist History [podcast], Episode 45. Pushkin Industries, 2023. [viewed 2024-01-10]. Available from: https://www.pushkin.fm/show/revisionist-history.
Reference List Formatting
ISO 690 allows flexibility in reference list organization:
Numeric system: List references in order of first citation
Author-date system: List references alphabetically by author surname
Key elements:
Title the section appropriately (References, Bibliography, Works Cited)
Maintain consistent formatting throughout
Include all sources cited in the text
ISO 690 vs Other Styles
Feature | ISO 690 | APA | Chicago |
|---|---|---|---|
Governance | International standard | American Psychological Association | University of Chicago |
Flexibility | High (guidelines, not rules) | Low (prescriptive rules) | Medium |
Author format | CAPITALS optional | Surname, F. N. | Firstname Lastname |
Systems offered | 3 (numeric, author-date, notes) | 1 (author-date) | 2 (notes-bib, author-date) |
Legal citations | Excluded (country-specific) | Limited coverage | Extensive coverage |
Common Mistakes to Avoid
Inconsistent formatting: Choose one system and apply it throughout
Missing access dates: Online resources require [viewed Date] for dynamic content
Incomplete identifiers: Include DOIs, ISBNs, or persistent identifiers when available
Wrong date format: ISO 690 prefers YYYY-MM-DD or written dates; be consistent
Mixing systems: Don't combine numeric and author-date citations in the same document
Ignoring institutional guidelines: ISO 690 provides flexibility—your institution may have specific requirements within that framework
References
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION. ISO 690:2021: Information and documentation—Guidelines for bibliographic references and citations to information resources. 4th ed. Geneva: ISO, 2021.
Kaunas University of Technology Library. How to cite and prepare a list of references (ISO 690:2021). 2025.
GRAFIATI. ISO 690:2021 references generator. 2022. [viewed 2026-01-04]. Available from: https://www.grafiati.com/en/blogs/iso-690-2021-citation-generator/.
