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Difficult Cross Number Puzzles
by Giulio Zambon

ISBN: 78-1-4826-7380-7
Publisher: MatheMagics Asia
Published in: 2013. Pages: 338.
Available in print from the publisher and from Amazon.

One hundred and fifty 8x8 puzzles for experienced solvers.

Cross Number is like any normal crossword puzzle. You must solve the clues to be able to write the answers in the grid, like in the example below.