@article{JIS_2009__12_4_a6,
     author = {Ayyer, Arvind},
     title = {Towards a human proof of {Gessel's} conjecture},
     journal = {Journal of integer sequences},
     publisher = {mathdoc},
     volume = {12},
     number = {4},
     year = {2009},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2009__12_4_a6/}
}