@article{MAN_1983__264_163766,
     author = {Tauno Mets\"ankyl\"a},
     title = {An {Upper} {Bound} for the {...-Invariant} of {Imaginary} {Abelian} {Fields.}},
     journal = {Mathematische Annalen},
     pages = {5--8},
     publisher = {mathdoc},
     volume = {264},
     year = {1983},
     zbl = {0497.12002},
     url = {http://geodesic.mathdoc.fr/item/MAN_1983__264_163766/}
}