Blog post by mathematician Terence Tao (a former instructor of Danica McKellar) complimenting Danica's book and explaining the theorem.
usnews.com
USNEWS.COM. USNEWS.COM: America's Best Colleges 2006: College Flashback: Danica McKellar. 2006. [1]
web.archive.org
Chayes, L., McKellar, D. & Winn, B. (1998) Percolation and Gibbs states multiplicity for ferromagnetic Ashkin-Teller models on
Z 2
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. Journal of Physics A: Mathematics and General, 31, 9055-9063. Full text as PDF