@article{10_37236_1697,
     author = {N. Calkin and C. Merino and S. Noble and M. Noy},
     title = {Improved bounds for the number of forests and acyclic orientations in the square lattice},
     journal = {The electronic journal of combinatorics},
     year = {2003},
     volume = {10},
     doi = {10.37236/1697},
     zbl = {1020.05041},
     url = {http://geodesic.mathdoc.fr/articles/10.37236/1697/}
}