@article{KYB_1968_4_6_a1,
     author = {Havel, Ivan M.},
     title = {Regular expressions over generalized alphabet and design of logical nets},
     journal = {Kybernetika},
     pages = {516--537},
     year = {1968},
     volume = {4},
     number = {6},
     mrnumber = {0247956},
     zbl = {0169.31504},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/KYB_1968_4_6_a1/}
}