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]