@article{MZ_1988__200_3_174006,
     author = {Dirk Ferus and Ulrich Pinkall},
     title = {Constant {Curvature} 2-spheres in the 4-sphere.},
     journal = {Mathematische Zeitschrift},
     pages = {265--272},
     year = {1988},
     volume = {200},
     number = {3},
     zbl = {0664.53029},
     url = {http://geodesic.mathdoc.fr/item/MZ_1988__200_3_174006/}
}