@article{ELMA_1969__24_140910,
     author = {O. Bottema},
     title = {A {Theorem} of {Bobillier} on the {Tetrahedron.}},
     journal = {Elemente der Mathematik},
     pages = {6--10},
     publisher = {mathdoc},
     volume = {24},
     year = {1969},
     zbl = {0165.23902},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1969__24_140910/}
}