@article{CM_1985__56_2_233_0,
     author = {Lassak, Marek},
     title = {Relative extreme subsets},
     journal = {Compositio Mathematica},
     pages = {233--236},
     publisher = {Martinus Nijhoff Publishers},
     volume = {56},
     number = {2},
     year = {1985},
     mrnumber = {809868},
     zbl = {0546.52001},
     language = {en},
     url = {http://archive.numdam.org/item/CM_1985__56_2_233_0/}
}