@article{ARM_1988_24_1_a0,
     author = {Zelinka, Bohdan},
     title = {Tolerances of polyunary algebras},
     journal = {Archivum mathematicum},
     pages = {1--4},
     year = {1988},
     volume = {24},
     number = {1},
     mrnumber = {983002},
     zbl = {0666.08002},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ARM_1988_24_1_a0/}
}