Ritschel, T.
Trinckauf, J.
Koepernik, K.
Büchner, B.
Zimmermann, M. v.
Berger, H.
Joe, Y. I.
Abbamonte, P.
Geck, J.
Article History
Received: 21 October 2014
Accepted: 30 January 2015
First Online: 16 March 2015
Competing interests
: The authors declare no competing financial interests.