@article{ITA_1989__23_1_87_0,
     author = {Jenner, Birgit and Kirsig, Bernd},
     title = {Characterizing the polynomial hierarchy by alternating auxiliary pushdown automata},
     journal = {RAIRO - Theoretical Informatics and Applications - Informatique Th\'eorique et Applications},
     pages = {87--99},
     publisher = {EDP-Sciences},
     volume = {23},
     number = {1},
     year = {1989},
     mrnumber = {990069},
     zbl = {0665.68038},
     language = {en},
     url = {http://archive.numdam.org/item/ITA_1989__23_1_87_0/}
}