1. Borel, A.: Seminar on transformation groups, Ann. Math. Studies, Princeton Univ. Press, 1960.
2. Helgasson, S.: Differential geometry and symmetric spaces, New York and London, Academic Press, 1962.
3. Lojasiewicz, S.: Ensembles semi-analitiques, Cours Faculté des Sciences d'Orsay, (mimeo.), 1965.
4. Mather, J.: Notes on topological stability (Chapter I), (mimeo.), Harward, 1970.
5. Milnor, J.: Singular points of complex hypersufaces, Ann. Math. Studies, Princeton Univ. Press, 1968.