@article{10_1090_S0894_0347_05_00507_2,
     author = {Berrick, A. and Cohen, F. and Wong, Y. and Wu, J.},
     title = {Configurations, braids, and homotopy groups},
     journal = {Journal of the American Mathematical Society},
     pages = {265--326},
     year = {2006},
     volume = {19},
     number = {2},
     doi = {10.1090/S0894-0347-05-00507-2},
     url = {http://geodesic.mathdoc.fr/articles/10.1090/S0894-0347-05-00507-2/}
}