@article{10_37236_1093,
     author = {Jakob Jonsson},
     title = {Hard squares with negative activity and rhombus tilings of the plane},
     journal = {The electronic journal of combinatorics},
     year = {2006},
     volume = {13},
     doi = {10.37236/1093},
     zbl = {1096.05004},
     url = {http://geodesic.mathdoc.fr/articles/10.37236/1093/}
}