Geodesic
Flexible Cross-Polytopes in the Euclidean 4-Space
Journal for geometry and graphics, Tome 4 (2000) no. 2, pp. 159-168 
H. Stachel. Flexible Cross-Polytopes in the Euclidean 4-Space. Journal for geometry and graphics, Tome 4 (2000) no. 2, pp. 159-168. http://geodesic.mathdoc.fr/item/JGG_2000_4_2_a5/
@article{JGG_2000_4_2_a5,
     author = {H. Stachel},
     title = {Flexible {Cross-Polytopes} in the {Euclidean} {4-Space}},
     journal = {Journal for geometry and graphics},
     pages = {159--168},
     year = {2000},
     volume = {4},
     number = {2},
     url = {http://geodesic.mathdoc.fr/item/JGG_2000_4_2_a5/}
}
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Voir la notice de l'article provenant de la source Heldermann Verlag

It is shown that the examples presented 1998 by A. Walz are special cases of a more general class of flexible cross-polytopes in E4. The proof is given by means of 4D descriptive geometry. Further, a parameterization of the one-parameter self-motions of Walz's polytopes is presented.