Because the physical book is out of print and famously heavy (often described as a "brick"), many modern players seek versions to facilitate digital training. A PGN version allows you to: Four Exercises From Polgar's Chess Middlegames
Epaulet mates, back-rank weaknesses, double attacks, and Sicilian sacrifices. Laszlo Polgar Chess Middlegames Pgn
Isolated Queen Pawns (168 positions), Hedgehog structures (108 positions), and Hanging Pawns. Because the physical book is out of print