When I insert a citation in my text, it is desplayed as . (name of the author, publication year)

Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. (Lincoln, Abraham, 1883)

I would like it to be displayed as a number sequentially, as it is usually displayed in books.

Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. 1

How can I do that?

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

If you're referring to how the citation is displayed in the text (and in the bibliography), that is controlled by setting the appropriate referencing Style. Numbering along the lines you seem to want is part of the IEEE 2006 & ISO 690 definitions.

The other possibility that come to mind is that your numbers are intended to refer to footnotes or endnotes, in which case, that what you should insert, then add your citations to those.

Note that some referencing systems are intended for the body text only, or for footnotes/endnotes only, and you can't use different systems in the same document.

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Cheers,
Paul Edstein
[Fmr MS MVP - Word]