Thony, C. (January 8, 2011). "Spotting the spots". The Renaissance Mathematicus. Archived from the original on July 21, 2011. Retrieved August 9, 2011.
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Thony, C. (January 8, 2011). "Spotting the spots". The Renaissance Mathematicus. Archived from the original on July 21, 2011. Retrieved August 9, 2011.