There are two basic systems for organizing Reference Number citations in a document: alphanumeric and numbered references.
For reference number citations, repeated citations in the text are assigned the same number.
Example: Numbered references:
For numbered references, the reference list is ordered in the order of their appearance in the paper:
Nothing seemed so certain as the results of the early studies (1). It was precisely this level of apparent certainty, however, which led to a number of subsequent challenges to the techniques used to process the data (2). There were a number of fairly obvious flaws in the data's aspect: consistencies and regularities that seemed most irregular, upon close scrutiny (1,2).To write Reference Number intext citations, and a numbered reference list in order of the appearance of the citations in the document::
1. Smith, J.P. Studying certainty. Science and Culture 9 (1989) 442.
2. Jones, M.R. Cooking the data? Science News 8 (1990) 878.
For ICMJE numbered cites, with a numbered reference list in order of the citations in the text:
If you have included specific page references in your Access keys, Citation will ignore these for Reference Number citations.