The Royal Society of Chemistry (RSC) Reference Style uses a system of superscript numbers in text when you are citing a work, and a reference list at the end of your document.  Use the same superscripted number for subsequent citations of the same work.

Numerical citations - Numerical references are given within the text as superscripted number.

If you cite the same source more than once, use the same citation number for all citations.

In-text numbers are matched to an entry in the Reference List

Reference List:

• Comes at the end of your document;
• Lists all the sources you have cited;
• Lists publications in the order they are given in your text (not alphabetically), giving a numerical reference followed by the full reference for the publication you are citing;
• Contains full details of the sources you have cited.