Hard Squares with Negative Activity and Rhombus Tilings of the Plane.

Jakob Jonsson Hard Squares with Negative Activity and Rhombus Tilings of the Plane. 2006 13 Electr. J. Comb. 1 http://www.combinatorics.org/Volume_13/Abstracts/v13i1r67.html db/journals/combinatorics/combinatorics13.html#Jonsson06