@article{MAN_1982__260_163657,
     author = {Patricia L. Sipe},
     title = {Roots of the {Canonical} {Bundle} of the {Universal} {Teichm\"uller} {Curve} and {Certain} {Subgroups}  of the {Mapping} {Class} {Group.}},
     journal = {Mathematische Annalen},
     pages = {67--92},
     publisher = {mathdoc},
     volume = {260},
     year = {1982},
     zbl = {0502.32017},
     url = {http://geodesic.mathdoc.fr/item/MAN_1982__260_163657/}
}