Universities with chess clubs (like University of Texas, Dallas, or Oxford) often host PDF libraries of public domain endgame studies.
Books by José Raúl Capablanca ( Chess Fundamentals ) and Wilhelm Steinitz are in the public domain. You can download legal PDFs of these masters' endgame chapters. Search for "Capablanca endgame lessons PDF."
Remember this: In a tournament, when 90% of players panic in the endgame, you will remain calm. You will see the opposition, the square of the pawn, the fortress. Your opponent, who only studied openings, will crumble.
Set up the diagrams from your PDF on a physical chess board. Play both sides. If the puzzle is "White to Win," play Black's best defense. This teaches resilience.
Start your endgame transformation today. Find a PDF, set up a board, and learn to finish what you started. [You can insert a short bio here, or a call-to-action to download a specific PDF if you have one to offer.]