Example of a Print Journal:
In-Text Citation: (Scruton, 1996) OR, if you used a quote: (Scruton, 1996, p.7)
Reference: Scruton, R. (1996). The eclipse of listening. The New Criterion, 15(3), 5-13.
Example of an Online Journal:
In-Text Citation: (Baniya & Weech, 2019) OR, if you used a quote: (Baniya & Weech, 2019, pp.14-15)
Reference: Baniya, S., & Weech, S. (2019). Data and experience design: Negotiating community-oriented digital research with service-learning. Purdue Journal of Service-Learning and International Engagement, 6(1), 11–16. https://www.jstor.org/stable/26537363
Examples from Purdue's OWL website.
The reason you need to "read" a citation is so you can find the article being cited. Researchers often use the references list at the end of a paper to find other articles for their own work.
To give you some hands-on experience, below is a citation for each group. Use the information in the citation to find the article it is citing in the American Journal of Physics. When you find it, let me know!