@article{MS2_1962__11_165818,
     author = {Fr. Fabricius-Bjerre},
     title = {On the {Double} {Tangents} of {Plane} {Closed} {Curves.}},
     journal = {Mathematica Scandinavica},
     pages = {113--116},
     publisher = {mathdoc},
     volume = {11},
     year = {1962},
     zbl = {0173.50501},
     url = {http://geodesic.mathdoc.fr/item/MS2_1962__11_165818/}
}