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Chess Tactics for Champions: A step-by-step guide to using tactics and combinations the Polgar way
by Susan Polgar
There is a preview on Amazon
If you will use your brain to solve all problems, it is worth to get the book. I used it with my son.
You read a chapter about one theme, then you solve problems.
Your 800 rating means that you are not novice. Though you still need a lot to learn and practice. The book will help. If you can try not even setup positions on the board. It will save some time. If you will find difficult positions only then put it on your board.
Try one chapter from a preview. If you like it , get it.
I have a copy of this book and it is really good to get acquainted with basic tactical patterns, but as mentioned by NM ZaidejasChegis you need to use your brain to solve all problems. That's the only way to make any progress.
In the end any tactical training, in which you use your brain to solve the problems (in stead of just guessing), will make you better at the game. Perhaps "a course in chess tactis", by Dejan Bojkov and Vladimir Georgiev is also a good choise.
Get a copy of "Bobby Fischer teaches Chess" and go all the way through it. It's in workbook format and can be picked up used for a couple bucks on Ebay. Just be sure it hasn't been written in by previous owners.
Yes that is a good book for you. It will improve your tactics..
I have the book signed by her. She came to one of my uscf tournaments and was selling them for $15. I also like how there is a chess rating scale on the back.