@article{ITA_1993__27_1_49_0,
     author = {Brandenburg, Franz J. and Dassow, J\"urgen},
     title = {Efficient reductions of picture words},
     journal = {RAIRO - Theoretical Informatics and Applications - Informatique Th\'eorique et Applications},
     pages = {49--56},
     publisher = {EDP-Sciences},
     volume = {27},
     number = {1},
     year = {1993},
     mrnumber = {1213420},
     zbl = {0770.68081},
     language = {en},
     url = {http://www.numdam.org/item/ITA_1993__27_1_49_0/}
}