1. B. Anderson et G. Hector: Groups which act analytically on the circle, article non publié.
2. Poincaré Bendixson theory for leaves of codimension one;Cantwell;Trans. A.M.S.,1981
3. Transverse foliations of Seifert bundles and self homeomorphisms of the circle;Eisenbud;Comment. Math. Helvetici,1981
4. E. Ghyset V. Sergiescu: Sur un groupe remarquable de difféomorphismes du cercle, a paraître dans Comment. Math. Helvetici.
5. Discontinuous groups and the Euler class;Goldman,1980