@article{DMTCS_2016_17_3_a20,
     author = {Brough, Tara and Ciobanu, Laura and Elder, Murray and Zetzsche, Georg},
     title = {Permutations of context-free, {ET0L} and indexed languages},
     journal = {Discrete mathematics & theoretical computer science},
     publisher = {mathdoc},
     volume = {17},
     number = {3},
     year = {2015-2016},
     doi = {10.46298/dmtcs.2164},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.46298/dmtcs.2164/}
}