An challenging collection of 344 large-format Sudoku puzzles,
with four different levels of difficulty from Very Easy to Difficult.
All the puzzles display symmetry in the manner in which their clues
are arranged on the grid, giving the puzzles a pleasing appearence.
A brief introduction gives some fascinating facts and figures, and
the first puzzle at each level is accompanied by some hints and by
an explanation of how it might be tackled.
The solution to each puzzle is printed in a final section.