Build Your Technique, by FM Thomas Wolski. 

Wolski follows his popular "Master Your Technique" with this new course which contains less difficult material. "Build Your Technique" is aimed at players with USCF or Elo ratings between 1200 and 1600, although some of the later challenges will not be easy for 1800 to 2000 rated players. The 110 challenges include some openings, middlegames, endgames, and a lot of tactics. This course is designed to enhance the overall understanding of chess for an intermediate player and to prepare that player for more advanced courses.

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