- Libraries list
- Accounts list
This page includes guidelines for two common citation styles, AIP and APA. If you are using another style and have questions, feel free to email the Science Librarian, Tessa Withorn (tessa.withorn@louisville.edu).
Ask your professor which style they would like you to use for your assignment. If you get to choose, I highly recommend APA!
This guide is a quick introduction to the American Institute of Physics (AIP) Style for in-text citations and references. Be sure to consult pages 8-9 of the AIP Style Manual for full details on citing sources in AIP Style.
Include a superscript number for each sequential reference where you cited the information at the end of the sentence, or next to the authors' last name. If there are more than two authors, use the abbreviation et al., which means "and others."
Hartouni et al.1 found that when plasma burns, ion relative kinetic energy distribution creates a Maxwell–Boltzmann distribution.
To add a superscript in Word, highlight the number, then click on the superscript option in the Font settings.
In some cases, you may also cite references in-text with the author's last names and year in parentheses. The reference list would then be ordered alphabetically.
List your references in numerical order at the end of your paper in a reference section. Citations will vary depending on the type of source.
1. Author(s), List names as first name initial(s) and last name. Use and before the last author. If there are more than four authors, use the abbreviation et al., which means "and others."
2. Abbreviated Journal Title. Some journal abbreviations will be included with the article information, otherwise look up the abbreviation of names in a search engine or Appendix G of the AIP Style Manual.
3. Volume, Only the number in bold.
4. Starting page number
5. (Year).
1E. P. Hartouni et al. Nat. Phys. 19, 72 (2023).
1. Author(s), List names as first name initial(s) and last name. Use and before the last author.
2. Book Title In italics and headline-style capitalization, meaning all important words are capitalized.
3. (Publisher, City of publication,
4. Year),
5. Volume, listed at Vol., # if any.
6. Starting page. Listed as p. x, if any.
2S. E. Hamen, Astronomy in the Real World (Abdo Publishing, North Mankato, 2016), p. 36.
There is no clear guidance on citing websites, as this is uncommon in published research. However, you can use the following general format.
1. Author or organization.
2. Title of Webpage. In italics.
3. URL
4. (accessed date). Use the format mm/dd/yyyy.
3American Museum of Natural History. What Is Astronomy?https://www.amnh.org/explore/ology/astronomy/what-is-astronomy (accessed 03/21/2023).
This guide is a quick introduction to the American Psychological Association (APA) Style for in-text citations and references. Be sure to consult the Publication Manual of the APA or the APA Style website for detailed standards and procedures.
You can also find sample papers with annotations and a Word template on APA Style's website.
Publication Manual of the American Psychological Association by When you reference another source, use an in-text citation in the body of your paper.
Paraphrasing or summarizing the main findings or takeaways from a research article is the preferred method of citing sources in an APA paper. Always include the last name of the author(s) and the year of the article, so your reader can find the full citation in the reference list. These citations can be written narratively or in parentheses at the end of the sentence. Any sentence punctuation goes after the closing parenthesis. See more examples of formatting parenthetical versus narrative in-text citations from APA Style's official website.
According to Shavers (2007), limitations of studying socioeconomic status in research on health disparities include difficulties in collecting data on socioeconomic status and the complications of classifying women, children, and employment status.
Limitations of studying socioeconomic status in research on health disparities include difficulties in collecting data on socioeconomic status and the complications of classifying women, children, and employment status (Shavers, 2007).
If you're quoting the exact words of someone else, include an in-text citation with the page number(s). See more examples of quotations from APA Style's website.
In-text citations differ depending on the number of authors listed for a work, and if there is a group author.
You only need the author's last name comma year in parentheses.
(Abrams, 2018)
Connect both authors' last names with & (ampersand) comma and the year.
(Wegener & Petty, 1994)
If there are 3 or more authors use et al., which is Latin for "and others," comma and the year.
(Harris et al., 2018)
First time with an abbreviation:
(Centers for Disease Control and Prevention [CDC], 2019)
Then all subsequent citations:
(CDC, 2019)
Include the complete citation at the end of your paper in a references section. References are organized by the author's last name in alphabetical (A-Z) order. Use an hanging indent to separate each list item.
Use the following directions and examples to format these common types of sources. You can find a comprehensive list of reference examples on APA's website.
1. Author(s). List each author's last name and initials as Author, A. A., Author, B. B., & Author, C. C. Use an ampersand (&) before the final author's name. Read more from the APA Style website if there are 21 or more authors.
2. (Year).
3. Title of the article. For works that are part of a greater whole (e.g. articles, chapter), use sentence case. Only the first word of the title and subtitle and proper nouns are capitalized.
4. Title of the Journal, Italicize and capitalize each word in the journal. You can use headline-style capitalization.
5. Volume Italicize the journal volume number. If there is no issue, include a comma before the page range.
6. (Issue), If there is a issue number in addition to a volume number, include it in parentheses.
7. Page range. If there is no page range within the journal volume/issue, this can be excluded.
8. DOI (Digital Object Identifier) This is a direct link to the article on the publisher's website. Read more about DOIs from APA Style's website.
Toledo, D., Sanderson, M., Spaeth, K., Hendrickson, J., & Printz, J. (2014). Extent of Kentucky bluegrass and its effect on native plant species diversity and ecosystem services in the Northern Great Plains of the United States. Invasive Plant Science and Management, 7(4), 543-552. https://doi.org/10.1614/IPSM-D-14-00029.1
1. Author(s). List each author's last name and initials as Author, A. A., Author, B. B., & Author, C. C. Use an ampersand (&) before the final author's name.
2. (Year).
3. Title of the book. Note: For works that stand alone (e.g. books, reports), italicize the title. Only capitalize the first word of the title and subtitle and any proper nouns.
4. (Edition). If there is an edition or volume, include it in parentheses and use abbreviations of ed. or vol.
5. Publisher. You do not need to include the publisher location or databases where you retrieved it.
Richtel, M. (2019). An elegant defense: The extraordinary new science of the immune system (1st ed.). William Morrow.
1. Author(s). List each chapter author's last name and initials as Author, A. A., Author, B. B., & Author, C. C. Use an ampersand (&) before the final author's name.
2. (Year).
3. Title of the chapter. For works that are part of a greater whole (e.g. articles, chapter), use sentence case. Only the first word of the title and subtitle and proper nouns are capitalized.
4. In Editor(s), List each editor's initials and last name as A. A. Editor, B. B. Editor, & C. C. Editors, include (Ed.) or (Eds.) in parentheses, and end with a comma.
5. Title of the book For works that stand alone (e.g. books, reports), italicize the title. Only capitalize the first word of the title and subtitle and any proper nouns.
6. (pp. xx-xx).
7. Publisher. You do not need to include the publisher location or databases where you retrieved it.
Khan, J. S., Provencher, J. F., Forbes, M. R., Mallory, M. L., Lebarbenchon, C., & McCoy, K. D. (2019). Parasites of seabirds: A survey of effects and ecological implications. In C. Sheppard (Ed.), Advances in marine biology (pp. 1-50). Academic Press.
1. Author(s). List each author's last name and initials as Author, A. A., Author, B. B., & Author, C. C. If there is no author, spell out the name of the organization or site.
2. (Year, Month Date). Read more about date formats from the APA Style website. Provide as specific a date as is available. Use the date last updated, but not the date last reviewed or copyright date. If there is no date, use (n.d.).
3. Title of page or section. Italicize the title of the page and use sentence case.
4. Source. Usually the official name of the website. If the source would be the same as the author, you can omit the source to avoid repetition.
5. URL
Healing Mushrooms. (n.d.). A comprehensive list of common wild mushrooms in Kentucky. https://healing-mushrooms.net/kentucky