@article{DMTCS_2009_special_256_a45,
     author = {Bousquet-M\'elou, Mireille and Claesson, Anders and Dukes, Mark and Kitaev, Sergey},
     title = {Unlabeled $(2+2)$-free posets, ascent sequences and pattern avoiding permutations},
     journal = {Discrete mathematics & theoretical computer science},
     publisher = {mathdoc},
     volume = {DMTCS Proceedings vol. AK, 21st International Conference on Formal Power Series and Algebraic Combinatorics (FPSAC 2009)},
     year = {2009},
     doi = {10.46298/dmtcs.2723},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.46298/dmtcs.2723/}
}