@article{CMH_1984__59_139971,
     author = {Christopher B. Croke},
     title = {A sharp four dimensional isoperimetric inequality.},
     journal = {Commentarii mathematici Helvetici},
     pages = {187--192},
     year = {1984},
     volume = {59},
     zbl = {0552.53017},
     url = {http://geodesic.mathdoc.fr/item/CMH_1984__59_139971/}
}