1. Configuration spaces;Fadell;Math. Scand,1962
2. On the homotopy groups of the union of spheres;Hilton;J. London Math. Soc.,1955
3. Immersions of manifolds;Hirsch;Trans. AMS,1959
4. Verschlingungsabbildungen im Euklidischen Raum;Kaiser,1988
5. Link maps in the 4-sphere;Kirk,1988