1. The invariance of the index in the metric space of closed operators;Cordes;J. Math. Mech.,1963
2. Vektorraumbündel und der Raum der Fredholm-Operatoren;Jänich;Dissertation Bonn,1964
3. On spaces having the homotopy type of a CW-complex;Milnor;Trans. Amer. Math. Soc.,1959
4. On the homotopy type of certain groups of operators;Palais;Topology,1964
5. The connectedness of the orthogonal group in Hilbert space;Putnam;Proc. Nat. Acad. Sci., Wash.,1951