Are you saying that you want footnotes? Use References tab | Cross-reference.

Or do you keep a list of references numbered 1, 2, 3, etc. and the same number may occur repeatedly in your document? In that case, set up a numbered list of your references at the end of the document and insert cross-references to the paragraph number through-out the text.

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Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional