@article{PMIHES_2003__98__105_0,
     author = {Chang, Sun-Yung A. and Gursky, Matthew J. and Yang, Paul C.},
     title = {A conformally invariant sphere theorem in four dimensions},
     journal = {Publications Math\'ematiques de l'IH\'ES},
     pages = {105--143},
     publisher = {Springer},
     volume = {98},
     year = {2003},
     doi = {10.1007/s10240-003-0017-z},
     mrnumber = {2031200},
     zbl = {1066.53079},
     language = {en},
     url = {http://www.numdam.org/articles/10.1007/s10240-003-0017-z/}
}