In the Vancouver system, more than 1 note identifier may occur at any single point in the text. A particular reference may be cited many times in the text, but always has the same number. The references may be assembled at the end of each chapter or section, or at the end of the document. The style to use for many reference types is described in Reference types in a reference list.
When citing references in the text:
- number them sequentially as they appear in the document
- use a superscript number after most punctuation in the text (eg after full stops and commas, but before a dash)
- separate in-text identifiers by commas
- use a hyphen for a number range (but not for 2 sequential numbers)
- do not use spaces.
Five methods have been described.2,3,7-9
In the reference list, precede each reference by a nonsuperscripted number.
If this style is used, superscript letters rather than numbers must be used for footnotes, to avoid confusion between references and footnotes. In the text, place notation letters for footnotes before numbers for references.
