APA citation style is used by many Physical and Social Science disciplines.
At the library: Publication manual of the American Psychological Association
Online: Visit the Purdue University Online Writing Lab (OWL) at https://owl.purdue.edu/
Some basic examples from the Purdue OWL site's APA Formatting and Style Guide (7th Edition):
APA format for citing an article in a journal:
Author, A. A., Author, B. B., & Author, C. C. (Year). Title of article. Title of Periodical, volume number(issue number), pages.
Scruton, R. (1996). The eclipse of listening. The New Criterion, 15(3), 5–13.
APA format for citing a book:
Author, A. A. (Year of publication). Title of work: Capital letter also for subtitle. Publisher Name. DOI (if available)
Stoneman, R. (2008). Alexander the Great: A life in legend. Yale University Press.
APA format for citing a webpage:
If the page names an individual author, cite their name first:
Lastname, F. M. (Year, Month Date). Title of page. Site name. URL
Price, D. (2018, March 23). Laziness does not exist. Medium. https://humanparts.medium.com/laziness-does-not-exist-3af27e312d01
If the resource was written by a group or organization, use the name of the group/organization as the author. Additionally, if the author and site name are the same, omit the site name from the citation.
Group name. (Year, Month Date). Title of page. Site name. URL
American Society for the Prevention of Cruelty to Animals. (2019, November 21). Justice served: Case closed for over 40 dogfighting
If the page's author is not listed, start with the title instead. Additionally, include a retrieval date when the page's content is likely to change over time (like, for instance, if you're citing a wiki that is publicly edited).
Title of page. (Year, Month Date). Site name. Retrieved Month Date, Year, from URL
Tuscan white bean pasta. (2018, February 25). Budgetbytes. Retrieved March 18, 2020, from https://www.budgetbytes.com/tuscan-white-bean-pasta/
If the date of publication is not listed, use the abbreviation (n.d.).
Author or Group name. (n.d.). Title of page. Site name (if applicable). URL
National Alliance on Mental Illness. (n.d.). Mental health conditions. https://www.nami.org/Learn-More/Mental-Health-Conditions