Skyscraper Sudoku [SKSU-4-009P]
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1000 Math Logic Puzzles – Collection I
US, CA; UK, DE, FR, ES, IT, other 
Puzzles in this book: Kakuro, From 1 to X, Doppelblock, Futoshiki, Sign In, Digital Battleships, Index Sums, Tenner Grid, Number Cross, and Grades.
