Harvard referencing is one of the most commonly adopted citation systems across universities in the UK. It follows an author–date format, meaning you cite a source by including the author’s surname and the year the work was published.
Harvard In-text Citation Examples
Let’s say you’re explaining that expanding access to solar power is one of the most effective ways to reduce household energy costs. This idea comes from a study written by Emma Clarke, published in 2016.
You can cite the source in two main ways:
Citation at the end
Expanding access to solar technology can significantly reduce household energy expenses (Clarke, 2016).Citation integrated into the sentence
Clarke (2016) argues that wider adoption of solar technology can reduce household energy costs.
Citing Multiple Authors
When a source has more than one author, the Harvard system changes slightly depending on how many authors are listed. Here’s how each version looks, along with a simple example of how it appears in a sentence.
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Single author |
Regular physical activity significantly improves mental health (Brown, 2018). |
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Two authors |
Regular physical activity significantly improves mental health (Brown and Patel, 2018). |
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Three authors |
Regular physical activity significantly improves mental health (Brown, Patel, and Nguyen, 2018). |
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Four or more authors |
Regular physical activity significantly improves mental health (Brown et al., 2018). |
Multiple Sources at the Same Point
Sometimes you may need to support a statement using more than one source. When this happens, list all the citations together and separate them with semicolons.
If you reference several sources at once, separate each with a semicolon.
Example
Renewable energy has become a central focus of national energy strategies (Turner, 2020; Ali et al., 2018; Rowe and Carter, 2011).
Multiple Works by the Same Author in the Same Year
Sometimes an author releases more than one publication in the same year. In these cases, add letters after the year to tell the sources apart.
When the same author publishes several works in one year, add letters after the date to distinguish them.
Example
Studies show a rapid increase in residential solar installations (Patel, 2015a; Patel, 2015b; Patel, 2015c).
Secondary References (Citing a Source You Found in Another Source)
Sometimes you want to reference an idea or quotation that you discovered in another author’s work, but you can’t access the original source. This is called secondary referencing. Harvard style allows this, but it should only be used when the original source is unavailable.
When using a secondary reference, you cite both authors in the text, but only include the source you actually read in your reference list.You read Patel’s 2020 book and it mentions a study by Green from 2012
Example
Studies have shown that early investment in renewable energy improves long-term sustainability (Green, 2012, cited in Patel, 2020).Reference List
Patel, R. (2020) Renewable energy strategies for the future. London: GreenTech Press.
Direct Quotes from Sources
If you are quoting text word-for-word, you must provide the relevant page number. This applies whether the quote comes from a single page or a range of pages.
For direct quotations, Harvard style requires page numbers. Use p. for a single page. Use pp. for multiple pages
Single-page quote
“Solar power remains one of the fastest-growing renewable technologies worldwide” (Nguyen et al., 2022, p. 14).Multi-page quote
“Solar power remains one of the fastest-growing renewable technologies worldwide” (Nguyen et al., 2022, pp. 14–16).
Citing AI tools like ChatGPT in Harvard style
Citing AI tools such as ChatGPT depends on how your university treats AI-generated content. Most institutions currently recommend citing it either as software or as a form of personal communication. Remember: Harvard style varies slightly across universities, so check your institution’s guidelines first.
Citing ChatGPT as Software (when discussing the tool itself)
In-text citation
ChatGPT is widely used to generate quick explanations for complex topics (OpenAI, 2025).Reference list entry
OpenAI (2025) ChatGPT [AI language model]. Available at: https://chat.openai.com/ (Accessed: 18 March 2025).
Citing ChatGPT as personal communication (Use this when you include text generated by ChatGPT)
In-text citation
Students should always fact-check outputs produced by generative AI systems (ChatGPT, 2025, personal communication, March 18, 2025).Reference list entry
Note: Personal communications are often not included in the reference list unless your institution requires it.
Citing a specific prompt (if required by your institution)
In-text citation
Wider adoption of solar technology can reduce household energy costs (ChatGPT, personal communication, March 18, 2025).Reference list entry
OpenAI (2025) ChatGPT response to the prompt: “Explain the impact of renewable energy adoption.” 18 March. Available at: https://chat.openai.com/.
Reference List
Your reference list should appear at the end of your work and include every source you cited. Arrange entries alphabetically by the author’s surname. Below is a brief example of Harvard-formatted references. For further information, read this blog.
References Formatted in Harvard Style
Journal article
Clarke, E. and Howard, D. (2019) ‘Trends in solar adoption across urban households’, Journal of Renewable Energy Studies, 45(2), pp. 112–124.Book
Patel, R. (2017) Renewable Energy Systems: A Practical Introduction. London: GreenTech Press.Website
EnergyUK (2022) How solar panels work. Available at: https://www.energyuk.org/solar-panels (Accessed: 15 March 2025).Conference paper
Lee, M., Carter, J. and Wilson, K. (2020) ‘Improving battery storage efficiency in residential areas’, in Proceedings of the International Conference on Sustainable Power Systems. Glasgow: IEEE, pp. 58–66.Thesis / Dissertation
Rahman, S. (2021) Assessing the Impact of Solar Microgrids in Rural Communities. PhD thesis. University of Manchester.Report
International Energy Board (2020) Global Renewable Energy Outlook 2020. Geneva: IEB Publications.YouTube Video
EcoFuture (2023) How Solar Batteries Store Energy [YouTube video]. Available at: https://www.youtube.com/watch?v=example123 (Accessed: 18 March 2025).Dataset
GreenDataLab (2022) Solar Installation Costs in Europe, 2010–2022. Available at: https://www.greendatalab.org/solar-costs (Accessed: 18 March 2025).Legislation
UK Government (2019) Renewable Energy Act 2019. London: The Stationery Office.
Conclusion
Mastering Harvard referencing becomes much easier once you understand the basic rules and work through a few clear example. Getting your references right also protects you from issues like plagiarism, which can happen when sources aren’t acknowledged properly.
If you’re unsure whether your work is fully original, you can run it through a plagiarism detector. And if you need help rewriting sentences in your own words while keeping the original meaning, a paraphrasing tool can make the process quicker and safer. For more guidance on Harvard referencing—and answers to common questions from students—feel free to continue to our FAQs section below, where we break down the rules even further.
