@article{CMH_1984__59_139966,
     author = {D.B.A. Epstein},
     title = {Commutators of {C...-diffeomorphisms.} {Appendix} to },
     journal = {Commentarii mathematici Helvetici},
     pages = {111--122},
     publisher = {mathdoc},
     volume = {59},
     year = {1984},
     zbl = {0535.58007},
     url = {http://geodesic.mathdoc.fr/item/CMH_1984__59_139966/}
}