Many good endgame book recommendations here.....(search 'endgame')...
Good Chess Books for Beginners and Beyond...
https://www.chess.com/blog/RussBell/good-chess-books-for-beginners-and-beyond
for focus on fundamental endgame principles I recommend "Endgame Workshop" by Bruce Pandolfini.
Also check out the section in the following article titled "Endgame Fundamentals"...
Improving Your Chess - Resources for Beginners and Beyond...
https://www.chess.com/blog/RussBell/improving-your-chess-resources-for-beginners-and-beyond
Can anyone recommend an endgame book about principles, strategy and tactics? How to approach the endgame.
It seems like endgame books have titles like 3 billion endgames you must know.