Zero Killer Sudoku book

Here is another unique book for the season! Zero Killer Sudoku puzzles are probably the most difficult sudoku variant and it has been 5 years since I published volume 1, which by the way, had a great reception, so it is definitely time for a new collection of the hardest killer sudoku puzzles. So, only Zero Killer sudokus, nothing else in this book. Mostly the usual zero killers, but some puzzles are a novelty and a surprise. I’ll give you a hint: in the final 5 puzzles, you will still play on a 9×9 grid, but you will not use the rule of 45! Anyway… here is the book… enjoy! 🙂 Oh, yes… there are a few puzzles labeled INSANE in this book!!!