Please advise the program for WinOS as a file manager that allows to create and store groups of downloaded papers and other references, so that it was possible to group them on multiple labels (tags)? Eg, sort by the author, and other categories: theoretical works, experimental, a methods like A, a methods like B... . The folder tree structure allows you to group only by one parameter. But ideally, I would like to do more than 10 categories.
I think, any databases allows to do that, but maybe exist simple solutions specialized for researchers?
I see there are a large variety of solutions
https://en.wikipedia.org/wiki/Comparison_of_reference_management_software
first of all, I need:
What programs do you use?