A source's citation includes the information necessary to identify and retrieve that source, including but not limited to:
The type of source being cited (books, journals, interviews, blogs, videos, social media, etc.) and the citation style being used will determine what the citation looks like. Choose an appropriate style guide for your needs. Here is an example of an article citation using four different citation styles:
Stokstad, Erik. "Can a Dire Ecological Warning Lead to Action?" Science (American Association for the Advancement of Science), vol. 364, no. 6440, 2019, pp. 517-518.
Stokstad, E. (2019). Can a dire ecological warning lead to action? Science (American Association for the Advancement of Science), 364(6440), 517-518. doi:10.1126/science.364.6440.517
Stokstad, Erik. 2019. "Can a Dire Ecological Warning Lead to Action?" Science (American Association for the Advancement of Science) 364 (6440): 517-518.
Stokstad E. Can a dire ecological warning lead to action? Science (American Association for the Advancement of Science). 2019;364:517-518.