The book must be very old because the notation is not in the currently de-facto standard Algebraic Notation. I tested some random positions but found the book’s solution not totally correct (besides hard to follow). This one for example, where the correct move should be Ne7+ but the book proposed Rxd7... then Nh6+

(FEN) r3r1k1/ppqn1ppp/2p2n2/4pN2/2P5/Q4PPB/PP1R1P1P/3R2K1 w - - 0 1

(could not copy the URL because it’s not permanent)