Since you have not clarified for us whether you are using a local host or just viewing the text file in the browser I will assume the latter.

In this case, you would have your anchor tag and in the href attribute put the location of the file

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In the above example I started from my C: drive and went from there. Also you could do it as follows:

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This should link to the pdf file that you have in mind, as long as the resources folder and html file are in the same folder