@article{KYB_1991__27_3_a2,
     author = {Fliess, Michel},
     title = {A simple definition of hidden modes, poles and zeros},
     journal = {Kybernetika},
     pages = {186--189},
     publisher = {mathdoc},
     volume = {27},
     number = {3},
     year = {1991},
     mrnumber = {1116832},
     zbl = {0746.93037},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/KYB_1991__27_3_a2/}
}