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Help
If you have any questions, you are always welcome to contact us. We'll get back to you as soon as possible, withing 24 hours on weekdays.
Customer service
All questions about your order, return and delivery must be sent to our customer service team by e-mail at yourstore@yourdomain.com
Sale & Press
If you are interested in selling our products, need more information about our brand or wish to make a collaboration, please contact us at press@yourdomain.com
Go way beyond difficult, with the hardest, most brainbusting sudoku youve ever seen!Calling all sudokusolving diehards: with every puzzle requiring upperlevel strategies, this collection packs even more of a punch than our previous Beyond Black Belt Sudoku. Get ready, because youll encounter common advanced techniques with curioussounding names like XYZWing, Finned XWing, Sashimi XWing, Swordfish, Jellyfish, Gordonian Rectangle, and Gordonian Polygon. And you might find some tricky new things here, too, from Grouped XCycle and Simple Grid Coloring to 3D Medusa and BiValue Universal Grave. The sudoku generally become increasingly difficult as the book goes along, from pretty darn hard to excruciating. Are you up for the challenge?
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birth defects, or other reproductive harm.
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support@ergodebooks.com
⚠️ California Proposition 65 Warning: Some products sold on this website may expose you to chemicals known to the State of California to cause cancer, birth defects, or other reproductive harm. For more information, visit www.P65Warnings.ca.gov.
