@article{CMUC_1971_12_2_a4,
     author = {Charv\'at, Franti\v{s}ek},
     title = {On problems concerning uniqueness of the extension of linear operations on linear spaces},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {271--280},
     year = {1971},
     volume = {12},
     number = {2},
     mrnumber = {0284826},
     zbl = {0232.47014},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1971_12_2_a4/}
}