@article{CMUC_1979__20_3_a15,
     author = {Simon, Petr},
     title = {Left-separated spaces: a comment to a paper of {M.} {G.} {Tka\v{c}enko}},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {597--604},
     publisher = {mathdoc},
     volume = {20},
     number = {3},
     year = {1979},
     mrnumber = {550459},
     zbl = {0444.54003},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1979__20_3_a15/}
}