@article{JRAM_1984__352_152656,
     author = {Johan P. Hansen},
     title = {Double-points of compositions.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {71--80},
     publisher = {mathdoc},
     volume = {352},
     year = {1984},
     zbl = {0534.14003},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1984__352_152656/}
}