Skip to Main Content

Physics: Cite Sources

Research guide for physics students

APA Citations

APA (American Psychological Association) citation style is most commonly used to write papers and cite sources in psychology, social sciences, and health disciplines.

  • Reference list: Include a full list of your sources at the end of your paper.
  • In-text citations: Use in-text citations when you quote, paraphrase, or summarize to let the reader know that the information comes from another source.

See the MC Library guide on APA Citations or one of the other resources below for more information.
Always check with your course instructor to verify which style you should use when writing a paper.

Quoting, Paraphrasing & Summarizing

Quoting Sources

When you quote a source, use "quotation marks" around the author's exact words (just as they are).

Include signal phrases and an in-text citation to show where the quote is from.

Paraphrasing & Summarizing Sources

When you paraphrase or summarize a source, you restate the source's ideas in your own words and sentence structure. Do not use quotation marks.

Changing only a few words is not sufficient. Instead, you need to completely rephrase the author's ideas in your own words. Select what is relevant to your topic, and restate only that.

But, you do not not need to change names, nouns, or scientific terms, these stay the same.


  • Stephen Hawking (a person's name)
  • Washington, DC (name of a place)
  • lungs (a noun)
  • trees (a noun)
  • periodic table (scientific term)
  • cellular respiration (scientific term)

Always use in-text citations when you paraphrase or summarize, to let the reader know that the information comes from another source. Continue to use signal phrases as well.

Step 4: Cite Sources

"Cite Sources." Laptop, mouse, and pencils.

The final step in the research cycle is to cite your sources. This step shows your reader that you've done proper research by listing sources you used to get your information.

Citing sources provides credibility to your ideas and places them in an academic context. It is also an important part of academic integrity. Giving credit to other researchers and acknowledging their ideas avoids plagiarism.

Citation Tools

More Citation Help

MC Writing, Reading, & Language Centers
Tutors at the WRL Centers can provide feedback on your writing, including questions on properly citing your sources.

Purdue Online Writing Lab (OWL)
Includes tutorials, sample papers, and sample bibliographies for all major citation styles.

MC Academic Integrity Resources