@article{ITA_1987__21_4_419_0,
     author = {K\"obler, Johannes and Sch\"oning, Uwe and Wagner, Klaus W.},
     title = {The difference and truth-table hierarchies for {NP}},
     journal = {RAIRO - Theoretical Informatics and Applications - Informatique Th\'eorique et Applications},
     pages = {419--435},
     publisher = {EDP-Sciences},
     volume = {21},
     number = {4},
     year = {1987},
     mrnumber = {928769},
     zbl = {0642.03024},
     language = {en},
     url = {http://archive.numdam.org/item/ITA_1987__21_4_419_0/}
}