Answer: Because in this way, you attach a scientific background to your text.
Explanation:
In this way, your work has a particular academic value. If the text is supported by valid literature that is broadcast through the list of references and footnotes in the text itself, then, in that case, we can talk about the validity of the document. In this case, we also leave room for other researchers who may eventually use your work to facilitate and simplify their search for professional literature. This method of presenting guidelines is called the "Vancouver System" and has been in use since 1978.
