1. Immersions of manifolds;Hirsch, Morris W.;Trans. Amer. Math. Soc.,1959
2. An approach to the enumeration problem for non-stable vector bundles;James, Ioan;J. Math. Mech.,1965
3. A relation between obstructions and functional cohomology operations;Little, Robert D.;Proc. Amer. Math. Soc.,1975
4. Torsion elements and the classification of vector bundles;Little, Robert D.;Canadian J. Math.,1977
5. J. Milnor, Lectures on characteristic classes, mimeographed notes, Princeton Univ., Princeton, N. J., 1957.