@article{KYB_2012__48_3_a4,
     author = {Melichar, Bo\v{r}ivoj and Janou\v{s}ek, Jan and Flouri, Tomas},
     title = {Arbology: {Trees} and pushdown automata},
     journal = {Kybernetika},
     pages = {402--428},
     publisher = {mathdoc},
     volume = {48},
     number = {3},
     year = {2012},
     mrnumber = {2975797},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/KYB_2012__48_3_a4/}
}