%0 Journal Article %A Robert Kaufman %T Metric properties of some planar sets %J Colloquium Mathematicum %D 1971 %P 117-120 %V 23 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.4064/cm-23-1-117-120/ %R 10.4064/cm-23-1-117-120 %G en %F 10_4064_cm_23_1_117_120