KenKen No-Ops: Sneaky 6x6s and More

This is a good intro to the No-Ops puzzles... I had already tried more challenging ones so this was a bit too easy for me

It is a nice and challenging book, but also not too hard. I bought this book for a train trip we would be taking and it worked out great. I wish the book was easier to write on like a workbook because it was like erasing and writing in a book!