Librería Samer Atenea
Kálamo Books
Librería Elías (Asturias)
Librería Kolima (Madrid)
Librería Proteo (Málaga)
Sudoku puzzles are highly addictive because the instructions are unchanging regardless of the degree of difficulty. For this set, however, expect to work on hard to extra hard challenges. Remember that Sudoku does not come with clues so you really have to figure out the answers on your own. Of course, there’s no rule saying you can’t ask help. You definitely can!