1. Bochnak, J., Coste, M., Roy, M.F.: Géométrie Algébrique Réelle. Springer, Berlin Heidelberg New York, 1987
2. Bröcker, L.: On the reduction of semialgebraic sets by real valuations. To appear.
3. Cherlin, G., Dickmann, M.: Real closed rings II. Model theory. Annals of pure and applied Logic 25, 213–231 (1983)
4. Delfs, H., Knebusch, M.: On the homology of algebraic varieties over real closed fields. J. reine angew. Math. 335, 122–163 (1982)
5. Dold, A.: Lectures on Algebraic Topology. Springer, Berlin Heidelberg New York 1972