@article{SF_1982__24_134535,
     author = {J. Rhodes and J. Karnofsky},
     title = {Decidability of complexity one-half for finite semigroups.},
     journal = {Semigroup forum},
     pages = {55--66},
     year = {1982},
     volume = {24},
     zbl = {0503.20028},
     url = {http://geodesic.mathdoc.fr/item/SF_1982__24_134535/}
}