@article{ASENS_1999_4_32_4_433_0,
     author = {Rebelo, Julio C.},
     title = {Ergodicity and rigidity for certain subgroups of ${\rm Diff}^\omega (S^1)$},
     journal = {Annales scientifiques de l'\'Ecole Normale Sup\'erieure},
     pages = {433--453},
     publisher = {Elsevier},
     volume = {Ser. 4, 32},
     number = {4},
     year = {1999},
     doi = {10.1016/s0012-9593(99)80019-6},
     mrnumber = {2000f:37031},
     zbl = {0968.37002},
     language = {en},
     url = {http://archive.numdam.org/articles/10.1016/s0012-9593(99)80019-6/}
}