The other answers cover book resources fairly well, however the OP also mentioned that
Not only books are suitable. If you can take courses, studies on Lichess, articles, etc. that would also be great.
With this in mind, I immediately thought of decodechess.com. DecodeChess explains the why behind chess moves in rich, intuitive language. Having tried it before, I found it fairly impressive, and definitely useful for reading along with books that leave out some of the strategic explanations that might be more obvious to readers with a more complete understanding.
From the website:
Performing a chess analysis with DecodeChess promotes the understanding of concepts and ideas that make up any position or move, serving as an on-the-go AI chess tutor for aspiring players in the ELO ranges of up to 2000.
I believe there are options to upload games in PGN/FEN formats, as well as analyze live while playing against a computer.