@article{10_21136_CMJ_1992_128320,
     author = {\v{Z}embery, Ivan},
     title = {Uniqueness of improper operations},
     journal = {Czechoslovak Mathematical Journal},
     pages = {19--23},
     publisher = {mathdoc},
     volume = {42},
     number = {1},
     year = {1992},
     doi = {10.21136/CMJ.1992.128320},
     mrnumber = {1152165},
     zbl = {0776.08004},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CMJ.1992.128320/}
}