@article{JRAM_1993__440_153536,
     author = {Kay Wingberg},
     title = {On the maximal unramified p-extension of an algebraic number field.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {129--156},
     publisher = {mathdoc},
     volume = {440},
     year = {1993},
     zbl = {0779.11054},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1993__440_153536/}
}