@article{ELMA_1973__28_141088,
     author = {G\"unter Ewald},
     title = {\"Uber geschlossene {Raumkurven} ohne einbeschriebenes {Parallelogramm.}},
     journal = {Elemente der Mathematik},
     pages = {14--14},
     publisher = {mathdoc},
     volume = {28},
     year = {1973},
     zbl = {0245.50011},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1973__28_141088/}
}