downloadfile An Essential to understanding chess openings!Pdf_module_version Ppi ScannerPDF download. Below you can go through all the moves on the chessboard and also download the PGN file with the chess games that we analyzed for this lesson to learn the essential theory about the London Systemd4 dc3 Nf chess and the interest to learn the openings and tactics suggested here, to make the best use of this book. In the second chapter, I have listed the key principles based on which chess strategi