Author starts with 24 pages of ideas and tactics on the Blumenfeld (where Black sacs b7-b5 to take over the center with Benoni-like play) before delving into the variation tree.  There he analyzes with a good balance of fragments, original analysis, and more explanation.   Ends with an appendix of unnumbered and uncommented games.   Figurine algebraic notation.   Index of players.  Bibliography.  107 pages