1. Category and generalized Hopf invariants;Berstein;Illinois J. Math.,1960
2. Lectures on Hilbert Cube Manifolds;Chapman,1976
3. Lusternik-Schnirelmann category and minimal coverings with contractible sets;Clapp;Manuscripta Math.,1987
4. Invariants of the Lusternik-Schnirelmann type and the topology of critical sets;Clapp;Trans. Amer. Math. Soc.,1986
5. A Course in Simple Homotopy Theory;Cohen,1973