Improve Your Tactics
Chessplayers. A great online database of tactical problems. You can't move the pieces, but then that's the point isn't it. This site includes databases with solutions including The Encyclopedia of Chess Middle Games, Bent Larsen's Good Move Guides, Endgame Studies, Positional Play, Reinfield's 1001 Winning Chess Sacrifices and Combinations and 1001 Ways to Checkmate. A great resource I recommend.
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