Purdue OWL:
An extensive citation guide used at colleges and universities.
https://owl.english.purdue.edu/owl/resource/747/01/
Modern Language Association (MLA):
The official website of the modern language association
Cabrillo College:
Cabrillo College has a plagiarism guide with very clear examples.
https://www.cabrillo.edu/services/writingcenter/Plagiarism.html#Examples