@article{10_37236_2017,
     author = {Alexander Burstein},
     title = {A short proof for the number of permutations containing pattern 321 exactly once},
     journal = {The electronic journal of combinatorics},
     year = {2011},
     volume = {18},
     number = {2},
     doi = {10.37236/2017},
     zbl = {1229.05006},
     url = {http://geodesic.mathdoc.fr/articles/10.37236/2017/}
}