Sudoku U: Junior Year  (English, Paperback, Longo Frank)

We'll school you in sudoku! Find your grade, improve your play-and graduate to the next level. Sudoku professor Frank Longo has crafted five books with 300 sudoku each, which will take students from solving basics to super-hard, super-expert strategies. Try them and see how far you can go! Things are getting tough here! Now solvers can put their skills to the test with 300 medium-hard to hard puzzles. By the end of the book you'll be working on upper-level techniques.