Whenever you start gathering text files for textual analysis, you must carefully consider if you have the legal right to use the resource for textual analysis. It can be a violation of copyright to use a copyrighted resource for text analysis, so it is best practice to use items that are in the public domain or that expressly state the the item is available for Data/Text mining.
Most practitioners of textual data anlytics will agree: finding textual data that is relevant to your research question, readily available in digital format, and not restricted by copyright or licensing is in many ways the hardest part of textual analytics. The sources below are good places to start, but if you're not finding what you are looking for, don't hesitate to reach out to a librarian for further consultation.
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