@article{CMUC_1971__12_1_a11,
     author = {Charv\'at, Franti\v{s}ek},
     title = {On problems concerning extension of linear operations on linear spaces},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {105--115},
     publisher = {mathdoc},
     volume = {12},
     number = {1},
     year = {1971},
     mrnumber = {0298391},
     zbl = {0232.47013},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1971__12_1_a11/}
}