@article{IM_1975__28_142317,
     author = {Manfred Herrmann and Rolf Schmidt},
     title = {Zur {Transitivit\"at} der normalen {Flachheit.}},
     journal = {Inventiones mathematicae},
     pages = {129--136},
     publisher = {mathdoc},
     volume = {28},
     year = {1975},
     zbl = {0278.14008},
     url = {http://geodesic.mathdoc.fr/item/IM_1975__28_142317/}
}