@misc{ELMA_1986__41_252004,
     title = {[unknown]},
     journal = {Elemente der Mathematik},
     pages = {81--82},
     publisher = {mathdoc},
     volume = {41},
     year = {1986},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1986__41_252004/}
}