@article{MM2_1982__40_154900,
     author = {Manfred Herrmann and Ulrich Orbanz},
     title = {Two {Notes} on {Flatness.}},
     journal = {Manuscripta mathematica},
     pages = {109--134},
     publisher = {mathdoc},
     volume = {40},
     year = {1982},
     zbl = {0525.13012},
     url = {http://geodesic.mathdoc.fr/item/MM2_1982__40_154900/}
}