Third method — software
In addition to the above methods to test the text for uniqueness, there is special software.
The DCFinder program (Double Content Finder) allows you to insert a text copied from the document or insert a link to an already published article to verify its uniqueness. Based on the results of the audit, the program will not only show how unique the text is, but also give out links to the pages in the results where coincidences were found.