@article{KYB_1979__15_3_a0,
     author = {Materna, Pavel},
     title = {An intensional approach to questions},
     journal = {Kybernetika},
     pages = {--192},
     publisher = {mathdoc},
     volume = {15},
     number = {3},
     year = {1979},
     mrnumber = {542174},
     zbl = {0412.03001},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/KYB_1979__15_3_a0/}
}