@article{MAN_1976__220_162821,
     author = {A. Koestner},
     title = {Beispiele von {Sph\"arenb\"undeln} \"uber {S2} .},
     journal = {Mathematische Annalen},
     pages = {211--214},
     publisher = {mathdoc},
     volume = {220},
     year = {1976},
     url = {http://geodesic.mathdoc.fr/item/MAN_1976__220_162821/}
}