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Academic Integrity - Referencing, Citation & Avoiding Plagiarism: Secondary Sources

This guide explains what referencing and citation is and how to use the APA, Chicago, Harvard, MLA and Vancouver Styles. It includes a short interactive tutorial on each style.

Secondary Sources

In general, it is recommended to read the original source or item being quoted, rather than relying on another source.

Where this is not possible, and one must rely on a "secondary source," then these are the available guidelines on how to cite it.
Reference: #. Author Last name Initials. Title. Edition. Place of publication: Publisher; Year of publication. pagination [i.e. how many pages are in the item].

25. Frogmantan, RW, Lewis, CS. The unusual case of how DNA was discovered. Dublin: Millar Press; 2007 641 p.
Use a superscript number (like this: ¹) in the text at the place where you are indicating that you are citing from a source.

Originally Crick and Watson, cited in Frogmantan and Lewis25, identified DNA. This was done by putting an onion in a juice machine and extracting a single onion cell.

Note: Vancouver Style does not have explicit guidelines for secondary sources. These rules have been adapted with kind permission of the University of York. See their Online Guide for full details.


Still unsure what in-text citation and referencing mean? Check here

Still unsure why you need to reference all this information? Check here.

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