When did Peter Armbruster find bohrium?

Bohrium was for the first time obtained by Gottfried Münzenberg, Sigurd Hofmann, Fritz Peter Hessberger, Willibrord Reisdorf, Karl-Heinz Schmidt, J.R.H. Schneider W.F.W. Schneider, Peter Armbruster, Christoph-Clemens Sahm, B. Thuma from Gesselschaft für Schwerionenforschung (Darmstadt, Germany) in 1981.