Before we start formatting references and in-text citations, let's step back and talk about why we cite sources in the first place, and what actually needs a citation.
Why we cite
When you write a paper, you're doing more than sharing your opinion. You're making an argument, and like any good argument, it needs evidence.
Citing your sources shows that your ideas are supported by research. If your reader wants to check your facts or see where an idea came from, they can follow your citation to the full reference and read the original. That's how academic writing works: someone proposes an idea, others review the evidence, and the idea either holds up or it doesn't.
It's also exactly what your professor does when grading your paper. You put forward a thesis, support it with research, and are evaluated on how well you build your case. Citing your sources makes your ideas stronger by showing they rest on credible evidence.
What happens if you don't cite?
When you use someone else's idea without giving them credit, even by accident, it's called plagiarism.
Plagiarism is a big deal in academic settings. Whether you meant to do it or not, failing to cite your sources can have serious consequences. The good news is that it's easy to avoid. Stay organized and cite any ideas, words, or visuals that aren't your own, and you'll be in the clear.
What should you cite?
Here's a simple rule: if it isn't your original idea or a widely known fact, you should probably cite it. That includes:
- Direct quotes
- Paraphrased or summarized ideas
- Data or statistics
- Images, charts, or graphs you didn't create
Basically, if it came from another source and it shaped your thinking or your paper, give credit where it's due.
And don't worry: citing other people's work doesn't weaken your paper. It strengthens it, because it shows you've done your research and are building on the work of others. Even if your whole idea is a new combination of things other people have said, that's still original, and worth sharing.
What it looks like in a paper
Here is a passage from the sample Bigfoot paper with each borrowed piece marked. Every one of them gets a citation.
Hair offered as proof of Bigfoot keeps matching animals we already know (Sykes et al., 2014).
Sykes et al. (2014) tested 30 hairs credited to Bigfoot and similar creatures. Every hair attributed to Bigfoot matched an animal already known to science.
A separate study reached a similar conclusion: “we nonetheless suspect that many Bigfoot sightings are, in fact, of black bears” (Lozier et al., 2009, p. 1626).
- A paraphrased ideaThe finding is in the writer's own words, so it gets the author and year.
- Data and statisticsNumbers come from the study, and the author is named in the sentence with the year beside it.
- A direct quoteThe exact words go in quotation marks, with the page number in the citation.
The in-text citations lesson covers each of these forms.
How PERRLA helps you cite
The hard part of citing is often keeping track of where things came from. With PERRLA's extension for Chrome and Edge, Add to PERRLA saves a source to your library from 85+ research databases, and a right-click saves a quote with it. When you write, each one is ready to cite. Before you submit, PERRLA reads the whole paper and points out any quote that still needs a citation or a page number.
Quotes missing citationsGo to
Quotes missing page numbersGo to
References never citedRemove
Click I'm Finished and PERRLA reads the whole paper against the APA rules. Go to takes you straight to each spot.