1. Bickel, H.: Four-dimensional stable planes with large point isotropy groups,submitted.
2. Dugundji J.:Topology (5th edn), Allyn & Bacon, Boston, 1970.
3. Grundh�fer, T. andL�wen, R.: Linear topological geometries, Chapter 23 in Buekenhout, F. (ed.),Handbook of incidence geometry, North-Holland, Amsterdam, 1995.
4. Grundh�fer, T. andStroppel, M.: On restrictions of automorphism groups of compact projective planes to subplanes,Results Math. 21 (1992), 319?327.
5. L�wen R.: Vierdimensionale stabile Ebenen,Geom. Ded. 5 (1976), 239?294.