Wikipedia documents how to add references and citations in 3 different ways: 1. Using <ref> tags and {{Reflist}} to add footnote references and a reference list. 2. Using {{Cite}} templates like {{Cite book}} to add citations that link to an internal or external ID. 3. Combining {{Cite}} templates with ref/sfnref to add a citation that links to an in-text footnote using ref and displays in a reference list using sfnref/sfn.