@article{MZ_1993__213_1_174545,
     author = {Joachim Gr\"ater},
     title = {Central extensions of ordered skew fields.},
     journal = {Mathematische Zeitschrift},
     pages = {531--556},
     publisher = {mathdoc},
     volume = {213},
     number = {1},
     year = {1993},
     zbl = {0789.12002},
     url = {http://geodesic.mathdoc.fr/item/MZ_1993__213_1_174545/}
}